Re: deleting from tarfile
Mark McEahern wrote: It doesn't appear so. A workaround, of course, is to create a new file with the subset of files from the old file: That is actually the *only* way to do that. tarfiles cannot be "sparse", in the sense that parts of the file can be marked as deleted. So in order to delete a file, you have to copy the entire tarfile, and skip the file you want to delete - whether you do this yourself, or whether tarfile.py does it for you. Regards, Martin -- http://mail.python.org/mailman/listinfo/python-list
generator expressions: performance anomaly?
Please consider the timings below, where a generator expression starts out slower than the equivalent list comprehension, and gets worse: >python -m timeit -s "orig=range(10)" "lst=orig[:];lst[:]=(x for x in orig)" 10 loops, best of 3: 6.84e+004 usec per loop >python -m timeit -s "orig=range(20)" "lst=orig[:];lst[:]=(x for x in orig)" 10 loops, best of 3: 5.22e+005 usec per loop >python -m timeit -s "orig=range(30)" "lst=orig[:];lst[:]=(x for x in orig)" 10 loops, best of 3: 1.32e+006 usec per loop >python -m timeit -s "orig=range(10)" "lst=orig[:];lst[:]=[x for x in orig]" 10 loops, best of 3: 6.15e+004 usec per loop >python -m timeit -s "orig=range(20)" "lst=orig[:];lst[:]=[x for x in orig]" 10 loops, best of 3: 1.43e+005 usec per loop >python -m timeit -s "orig=range(30)" "lst=orig[:];lst[:]=[x for x in orig]" 10 loops, best of 3: 2.33e+005 usec per loop Specs: Python 2.4, Windows 2000, 1.4GHz Athlon chip, 768Mb of memory. Background: There was/is a very recent thread about ways of removing all instances of x from a list. /F proposed a list comprehension to build the result list. Given a requirement to mutate the original list, this necessitates the assignment to lst[:]. I tried a generator expression as well. However while the listcomp stayed competitive up to a million-element list, the genexp went into outer space, taking about 20 times as long. The above timeit runs show a simpler scenario where the genexp also seems to be going quadratic. Comments, clues, ... please. TIA, John -- http://mail.python.org/mailman/listinfo/python-list
Re: How to del item of a list in loop?
John Machin wrote:
>> (if you have 2.4, try replacing [] with () and see what happens)
>
> The result is a generator with a name ("lst") that's rather misleading
> in the context.
according to my dictionary, the word "list" means "A series of names, words,
or other items written, printed, or imagined one after the other". I'd say that
matches both list objects and iterators pretty well.
but alright, you can change the name to "seq" if you want.
> Achieving the same result as the list comprehension, by doing lst = list(i for
... etc etc), appears to be slower.
the original post didn't contain a complete use case; a generator is a perfect
replacement for a list in many cases. I'm sure most comp.lang.python readers
are smart enough to understand when and why.
--
http://mail.python.org/mailman/listinfo/python-list
Re: generator expressions: performance anomaly?
John Machin wrote: > Given a requirement to mutate the original list, this necessitates the > assignment > to lst[:]. do you always pull requirements out of thin air? -- http://mail.python.org/mailman/listinfo/python-list
Re: How to del item of a list in loop?
John Machin wrote: Nick Coghlan wrote: The effbot's version is still going to be faster though: lst = [x for x in lst if x != 2] Have you measured this? Nope. I'm going purely on the fact that it is O(n), and the in-place modification will always be worse than that. Cheers, Nick. -- Nick Coghlan | [EMAIL PROTECTED] | Brisbane, Australia --- http://boredomandlaziness.skystorm.net -- http://mail.python.org/mailman/listinfo/python-list
Re: generator expressions: performance anomaly?
John Machin wrote: Background: There was/is a very recent thread about ways of removing all instances of x from a list. /F proposed a list comprehension to build the result list. Given a requirement to mutate the original list, this necessitates the assignment to lst[:]. I tried a generator expression as well. However while the listcomp stayed competitive up to a million-element list, the genexp went into outer space, taking about 20 times as long. The above timeit runs show a simpler scenario where the genexp also seems to be going quadratic. Comments, clues, ... please. Py> lc = [x for x in range(100)] Py> len(lc) 100 Py> ge = (x for x in range(100)) Py> len(ge) Traceback (most recent call last): File "", line 1, in ? TypeError: len() of unsized object It would be nice if unconditional ge's with known length inputs propagated __len__, but that is not currently the case. There's a similar performance glitch associated with constructing a tuple from a generator expression (with vanilla 2.4, detouring via list is actually faster) Cheers, Nick. -- Nick Coghlan | [EMAIL PROTECTED] | Brisbane, Australia --- http://boredomandlaziness.skystorm.net -- http://mail.python.org/mailman/listinfo/python-list
Re: How to del item of a list in loop?
On Sat, 15 Jan 2005 15:27:08 -0500, skull <[EMAIL PROTECTED]> wrote: > >Hi everybody, it is my first post in this newsgroup. >I am a newbie for python though I have several years development experience in >c++. >recently, I was stumped when I tried to del item of a list when iteration. > >here is the wrong way I did: > >lst = [1, 2, 3] >for i in lst: >print i >if i == 2: > lst.remove(i) > >the result is: > >1 >2 > >as you would see, '3' is missing. this problem is caused by 'lst.remove(i)'. >apparently, 'marked-and-sweep' is a solution to deal with this issue. >but I think there SHOULD BE more 'wise' trick. I want to get your help. > >Thanks in advance. > No one seems to have suggested this in-place way yet, so I'll trot it out once again ;-) >>> lst = [1, 2, 3] >>> i = 0 >>> for item in lst: ...if item !=2: ...lst[i] = item ...i += 1 ... >>> del lst[i:] >>> lst [1, 3] Regards, Bengt Richter -- http://mail.python.org/mailman/listinfo/python-list
Re: interpret 4 byte as 32-bit float (IEEE-754)
On Sat, 15 Jan 2005 11:00:36 -0800, Scott David Daniels <[EMAIL PROTECTED]>
wrote:
>G.Franzkowiak wrote:
>> Scott David Daniels schrieb:
>>
>>> franzkowiak wrote:
>>>
I've read some bytes from a file and just now I can't interpret 4
bytes in this dates like a real value. An extract from my program:
def l32(c):
return ord(c[0]) + (ord(c[1])<<8) + (ord(c[2])<<16) +
(ord(c[3])<<24)
...
value = l32(f.read(4)) <--- 3F 8C CC CD should be 1.11
>>> OK, here's the skinny (I used blocks & views to get the answer):
>>>
>>> import struct
>>> bytes = ''.join(chr(int(txt, 16)) for txt in '3F 8C CC CD'.split())
>>> struct.unpack('>f', bytes)
>>>
>>> I was suspicious of that first byte, thought it might be an exponent,
>>> since it seemed to have too many on bits in a row to be part of 1.11.
>>>
>>> -Scott David Daniels
>>> [EMAIL PROTECTED]
>>
>>
>> Ok, I the string exist with "mystr = f.read(4)" and the solution for
>> this case is in your line "struct.unpack('>f', bytes)"
>> But what can I do when I want the interpret the content from the Integer
>> myInt (*myInt = 0x3F8D) like 4-byte-real ?
>> This was stored with an othes system in a binary file to
>> CD CC 8C 3F and now is it in python in value. The conversion is not
>> possible. It's right... one of this bytes is an exponent.
>> I want copy the memory content from the "value address" to "myReal
>> address" and use print "%f" %myReal.
>> Is myReal then the right format ?
>> What can I do with python, in FORTH is it simple
>> ( >f f. )
>>
>> gf
>>
>>
>>
>If you really want to do this kind of byte fiddling:
> http://members.dsl-only.net/~daniels/block.html
>
>Then:
> from block import Block, View
> b = Block(4) # enough space for one float (more is fine)
> iv = View('i', b) # getting to it as an integer
> fv = View('f', b) # same memory as floating point
> iv[0] = 0x3F8D # Here is a sample just using the integer
> print fv[0]
>
>On an Intel/Amd/Generic "PC" machine, you should get 1.1
>
Ok, for most bit patterns (except QNANs), you can do it in pure python:
< i32as_single.py >
class NoQNAN(ValueError): pass # use to flag inability to return QNANs
def i32as_single(i):
"""
(UIAM in my interpretation of a 1995 Pentium Processor Developer's Manual)
This converts bits in a 32-bit integer as if they were bits
of a single-precision IEEE 754 floating point number to python float
+---+---+---+---+---+---+---+---+---+---+---+---+ ... +---+---+---+---+
| s | e e e e e e e eb| b b b ... b b b b0 |
+---+---+---+---^---+---+---+---^---+---+---+---^ ... ^---+---+---+---+
31 30 29 28 27 26 25 24 23 22 21 203 2 1 0
where s is the sign bit, and is the only thing that changes between + and -
and e..eb is an 8-bit biased (by 127) exponent, and eb is the hidden
unit 1 bit followed by 23 b..b0 significant "fraction" bits",
normalized so that the most significant bit is always 1 and therefore
doesn't have to be stored at eb, except that when all but the sign bit
are zero, eb is ignored and the value is then a signed zero value.
The binary fraction starting bit is after the hidden '1' bit eb at 23,
so viewing bits 0..23 as an integer, we have to divide by 2**23 (or
adjust the exponent) to get the 1. values when the official unbiased
exponent is zero (offset value 127). Thus 0x3f80 is zero unbiased
exponent and no other bits, for a value of 1.0
A biased exponent of 255 signifies a NaN, and a biased exponent of
zero signifies a denormal (which doesn't have a hidden bit, and whose
unit bit is bit 22). Single precision denormals can be normalized
in python (double) float format, which is done for the return value.
"""
signbit = i&0x8000
if not i&0x7fff: return signbit and -0.0 or 0.0 # if -0.0 available
biased_exp = (i>>23) & 0xff # bits 30-23
unitbit = biased_exp and 0x80 or 0 # bit 23, or 0 for denormals
significand = i & 0x7f # bits 22-0
if biased_exp == 255:
if significand:
raise NoQNAN, "Sorry, can't generate QNAN from %08x" % i
return signbit and -1e or 1e # XXX s/b INF's for sure??
adjexp = (biased_exp or 1) - 127 - 23 # adjusted for denormal
posvalue = (significand + unitbit)*2.0**adjexp
return signbit and -posvalue or posvalue
def test():
import struct
num = 0
for sign in (0, 2*(-2**30)):
for i3 in xrange(128):
num3 = i3<<24
for i2 in xrange(256):
print '\r%08x'%(num,), # show progress
num2 = i2<<16
# skip mid byte of significand, make 0
# and twiddle only a few bits at the bottom
for num0 in xrange(8):
num = sign+num3+num2+num0
Re: video analysis with python
Hello Ashot, > I need to write a video analysis tool which extracts statistics from > microsocope video. Essentially what I need is to translate the video data > into numerical matrices. I have been using Python for the past 1.5 years > anytime I could for absolutely everything, because it has every library > imaginable... Alas, I can not find a library for decoding video/using > codecs. The only solution I have been able to come up with is to create > an image sequence and load those in with PIL, however this is not really > feasible as the images are too large (nor is it proffessional). > > Is there a library or project that I have missed, or is there a way > to incorporate something like vfw.lib directly? If there isn't I > think > this would be a pretty large whole in Python's arsenal. Thanks in advance > for any help. 1. There is PyMedia (http://pymedia.org/) 2. Maybe you can use the code from VLC (http://www.videolan.org/vlc/) (using SWIG/PyBoost/Pyrex ...) HTH. -- Miki Tebeka <[EMAIL PROTECTED]> http://tebeka.bizhat.com The only difference between children and adults is the price of the toys -- http://mail.python.org/mailman/listinfo/python-list
Re: How to del item of a list in loop?
Bengt Richter wrote: > No one seems to have suggested this in-place way yet, > so I'll trot it out once again ;-) > > >>> lst = [1, 2, 3] > >>> i = 0 > >>> for item in lst: > ...if item !=2: > ...lst[i] = item > ...i += 1 > ... > >>> del lst[i:] > >>> lst > [1, 3] Works, but slowly. Here's another that appears to be the best on large lists, at least for removing 1 element. It's O(len(list) * number_to_be_removed). !def method_try_remove(lst, remove_this): !try: !while 1: !lst.remove(remove_this) !except: !pass -- http://mail.python.org/mailman/listinfo/python-list
accessing class variables of private classes
Hi, I need to access class variables of a class I'd like to make private: i.e. class __Bar(object): pass class __Foo(__Bar): def __init__(self): super(__Foo, self).__init__() >>> __Foo() Name Error: global name '_Foo__Foo' is not defined Here I want to prevent the user of instanciating __Foo from outside of the module. i.e. class __A: a_list = [] def __init__(self): __A.a_list.append(self) >>> __A() NameError: global name '_A__A' is not defined Here I want to keep a list of instanciated objects of class __A, so I can update internal values if they are changed. Any ideas? Thanks Uwe -- http://mail.python.org/mailman/listinfo/python-list
Re: there's a socket.sendall(), so why no socket.recvall()?
there's a socket.sendall(), so why no socket.recvall()? BTW socket.sendall() doesn't actually work for large amounts of data on Windows 2000 and probably other versions of Windows as well. Eg if you supply a 1MB buffer then you get an exception based on some internal Windows error code. I haven't experimented on Unix yet to see if it has the same issue. The workaround is to write a wrapper that really does send everything. Roger -- http://mail.python.org/mailman/listinfo/python-list
Newbie inheritance question.
Hi all, I'm a java programmer struggling to come to terms with python - bear with me! I'm trying to subclass a class, and I want to be able to see it's attributes also. Here are my classes: one.py: * class one: def __init__(self): print "one" self.testVar = 1 def printHello(self): print "hello" * two.py * from one import one class two(one): def __init__(self): print "two" def printTestVar(self): print "testVar: " + str(self.testVar) * and the driver to make it work: * from two import two class driver: def go(self): print "driver" self.two = two() self.two.printHello() self.two.printTestVar() if __name__ == '__main__': d = driver() d.go() * the "self.two.printTestVar()" call doesn't work: shouldn't two.py have access to all of it's parents attributes? In java I would make the testVar protected so it's children could see it. How do I do this in python? Thanks, Bones -- http://mail.python.org/mailman/listinfo/python-list
Re: accessing class variables of private classes
Uwe Mayer wrote: Hi, I need to access class variables of a class I'd like to make private: Use single underscores instead of double underscores--you won't have to workaround the name mangling. Besides, nothing's really private anyway. // m -- http://mail.python.org/mailman/listinfo/python-list
Re: Newbie inheritance question.
On Jan 16, 2005, at 9:08 AM, bwobbones wrote: class two(one): def __init__(self): print "two" You need to specifically call the superclass's __init__ here in order for it to fire. Just add the line super(two, self).__init__() as the first line of the subclass's __init__. ___/ / __/ / / Ed Leafe http://leafe.com/ http://dabodev.com/ -- http://mail.python.org/mailman/listinfo/python-list
Re: Newbie inheritance question.
bwobbones wrote: Hi all, I'm a java programmer struggling to come to terms with python - bear with me! Welcome! I'm trying to subclass a class, and I want to be able to see it's attributes also. Here are my classes: [snip] class two(one): def __init__(self): print "two" The problem is that you're not calling the parent class' __init__:: class two(one): def __init__(self): one.__init__(self) ... You can also use super() to do that, but I do that so rarely I forget the syntax. Of course, that's no big deal, since:: python >>> help(super) is always to the rescue, but I'm lazy. // m -- http://mail.python.org/mailman/listinfo/python-list
Re: there's a socket.sendall(), so why no socket.recvall()?
Roger Binns wrote: there's a socket.sendall(), so why no socket.recvall()? BTW socket.sendall() doesn't actually work for large amounts of data on Windows 2000 and probably other versions of Windows as well. Eg if you supply a 1MB buffer then you get an exception based on some internal Windows error code. I haven't experimented on Unix yet to see if it has the same issue. I suspect that this is related to this issue: http://www.python.org/sf/853507 socket.recv() raises MemoryError exception (WindowsXP ONLY) Also see: http://www.python.org/sf/1103350 But I haven't yet experienced this problem yet with sendall (on linux and windows xp) --Irmen -- http://mail.python.org/mailman/listinfo/python-list
Re: Newbie inheritance question.
In article <[EMAIL PROTECTED]>, Ed Leafe <[EMAIL PROTECTED]> wrote: > On Jan 16, 2005, at 9:08 AM, bwobbones wrote: > > > class two(one): > >def __init__(self): > >print "two" > > You need to specifically call the superclass's __init__ here in order > for it to fire. Just add the line > > super(two, self).__init__() > > as the first line of the subclass's __init__. super() only works for new-style classes, ie. class one needs to derive from object for this to work. Just -- http://mail.python.org/mailman/listinfo/python-list
Re: How to del item of a list in loop?
John Machin wrote: I've taken your code and improved it along the suggested lines, added timing for first, middle, and last elements, added several more methods, and added a testing facility as well. Would you like a copy? Actually I think it would be great if you posted it here for our combined edification. I would have been considerably less annoyed if you had done that and explained why it is better rather than nitpicking my version. -- Michael Hoffman -- http://mail.python.org/mailman/listinfo/python-list
Re: generator expressions: performance anomaly?
"John Machin" <[EMAIL PROTECTED]> wrote in message news:[EMAIL PROTECTED] > Please consider the timings below, where a generator expression starts > out slower than the equivalent list comprehension, and gets worse: > > >python -m timeit -s "orig=range(10)" "lst=orig[:];lst[:]=(x for x > in orig)" . . . > >python -m timeit -s "orig=range(20)" "lst=orig[:];lst[:]=(x for x > in orig)" This has nothing to do with genexps and everything to do with list slice assignment. List slice assignment is an example of a tool with a special case optimization for inputs that know their own length -- that enables the tool to pre-allocate its result rather than growing and resizing in spurts. Other such tools include tuple(), map() and zip(). The incredulous tone of the posting suggests a presumption that genexps always outperform list comps. That is not the case. Sometimes you want a list instead of a generator because you want more than just iteration; perhaps the consumer function may be able to take advantage of length reporting, indexing, slicing, re-iterability or other useful list behaviors. Also, the timing jig bites. Use xrange() instead of range(). Otherwise, there's an immediate forfeit of the memory savings normally being sought by the use of generators and iterators. > Background: There was/is a very recent thread about ways of removing > all instances of x from a list. /F proposed a list comprehension to > build the result list. FWIW, deques have a natural idiom for this kind of situation: for i in xrange(len(mydeque)): x = mydeque.popleft() if some_condition(x): mydeque.append(x) > Given a requirement to mutate the original list, > this necessitates the assignment to lst[:]. Sometimes people introduce arbitrary requirements and twist themselves in knots when real applications tend to allow a wider range of alternative solutions. There is a funky code smell emanating from any code resembling a[:]=some_iterator. It would make me examine how 'a' is being used and check whether the surrounding code can use the iterator or an new object. > Comments, clues, ... please. As a point of interest, note that Py2.4 improved some of its built-in iterators to report their length if requested. Now you now why. >>> d = dict(a=1, b=2, c=3, d=4) >>> len(d.iteritems()) 4 Raymond Hettinger -- http://mail.python.org/mailman/listinfo/python-list
iTools
Where can I download python-itools? I found it in the python packages index but the site is not contactable. Thank you. -- http://mail.python.org/mailman/listinfo/python-list
Re: interpret 4 byte as 32-bit float (IEEE-754)
[Bengt Richter]
...
> But I don't know how to build QNaNs:
You can subtract infinity from infinity. While all Python behavior in
the presence of NaNs, infinities, and signed zeroes is a
platform-dependent accident, it you're on a box that has such things,
and figure out some (accidental!) way to spell infinity, then inf-inf
should return a NaN (although on a WinTel box, it's most likely to be
spelled "-1.#IND" when converted to string).
...
> Whereas struct does:
No, it doesn't. All Python behavior in the presence of NaNs,
infinities, and signed zeroes is a platform-dependent accident.
> >>> import struct
> >>> struct.unpack('f','\x00\x00\x80\x7f')[0]
> 1.#INF
An accident (both that you got back an infinity, and the string
representation of an infinity).
> >>> struct.unpack('f','\x01\x00\x80\x7f')[0]
> 1.#QNAN
Ditto.
Those specific accidents are reliable on the box you're using.
> BTW, your example:
> >>> struct.unpack('f','\xcd\xcc\x8c\x3f')[0]
> 1.100238418579
> >>> i32f(0x3f8d)
> 1.100238418579
>
> But what does this mean?
Mostly just that behavior is predictable when you're *not* using
infinities, NaNs or signed zeroes from Python.
> (I wanted to test with little endian unpacking, since
> that is what I knew I created, but that isn't what '<' means?? ...)
Little-endian is part of what '<' means. '<' also means "use standard
alignment" and "use standard data size" and "use standard bit
representation". As soon as you force anything like that, Python has
to try to interpret the bits itself. In the absence of "<", ">" and
"!", plain "f" asks for a wholly platform-native result. In that
case, Python doesn't have to know anything about what the bits might
mean: it stores the bytes into a native sizeof(float)-byte memory
area natively aligned for a float, and you get back whatever the
native C thinks that means.
> >>> struct.unpack('f','\x00\x00\x80\x7f')[0]
> 1.#INF
Entirely determined by the platform C compiler and hardware.
> >>> struct.unpack(' 3.4028236692093846e+038
Entirely determined by what Python thinks the bits should mean, but
Python doesn't know anything about infinities, NaNs, or signed zeroes,
and C89 library routines Python calls to construct the value (like
ldexp()) have no portably defined behavior in their presence either.
--
http://mail.python.org/mailman/listinfo/python-list
Re: How can I get the names of the files in a directory?
På 15. jan 2005 kl. 16:16 skrev .removethis.:
>>> import glob
>>> from os.path import isfile
>>> print filter(isfile, glob.glob('/tmp/*')) # can use patterns
Nice example of when filter() is better than list comprehension.
[f for f in glob.glob("/tmp/*") if isfile(fi)]
is a bit too verbose, the iteration is a totally uninteresting part
here.
--
Stian Søiland
Trondheim, Norway
http://www.soiland.no/
=/\=
--
http://mail.python.org/mailman/listinfo/python-list
Re: accessing class variables of private classes
Uwe Mayer wrote: > I need to access class variables of a class I'd like to make private: > > i.e. > class __Bar(object): > pass > > class __Foo(__Bar): > def __init__(self): > super(__Foo, self).__init__() > __Foo() > Name Error: global name '_Foo__Foo' is not defined > > Here I want to prevent the user of instanciating __Foo from outside of the > module. > > > i.e. > class __A: > a_list = [] > def __init__(self): > __A.a_list.append(self) > __A() > NameError: global name '_A__A' is not defined > > Here I want to keep a list of instanciated objects of class __A, so I can > update internal values if they are changed. > > > Any ideas? Use single underscores. Even better: don't impose bogus restrictions on users of your module. I know, we're all dissenting children, but still... > > Thanks > Uwe -- http://mail.python.org/mailman/listinfo/python-list
Re: threading and sockets ?
http://www.twistedmatrix.com/ Daniel Bickett -- http://mail.python.org/mailman/listinfo/python-list
Re: mutable string?
Torsten Mohr wrote: is there some string class that i can change in place, like perls strings? array.array is mutable. You can use the 'c' code if you want an array of characters. Is it possible to do some regex replacement functions that would even change its length? You can't use re.sub array, but you can use re.search, and you can perform slice assigment. Can i append to this string? Yes. Is there some wrapper for C++ STL string class (if that would make sense)? It would be possible, but I cannot see why one would want to do that. Regards, Martin -- http://mail.python.org/mailman/listinfo/python-list
Re: why are some types immutable?
Torsten Mohr wrote: reading the documentation (and also from a hint from this NG) i know now that there are some types that are not mutable. But why is it this way? There are various reasons, some apply for some types, and some for others: - immutable objects are hashable - their hash value will not change during their life time (if it is a container, the contained objects also need to be hashable). Mutable types are typically not hashable. A type needs to be hashable to act as a dictionary key. - immutable objects can be shared, allowing the same reference to be used in multiple places. For mutable objects, one often needs to make a copy of the object before storing it. - immutable types can often be implemented more efficiently. For examples, the length of a tuple is fixed, as tuples are immutable. Therefore, memory management for tuples is simpler (they only require one memory block, instead of two, as lists do). - for some types, the expectation of immutability is so common that people would complain massively if they were mutable. This, in particular, applies to numbers - people expect that after x = 7 the variable x keeps the value, and that the "7" object cannot suddenly change its value to 8. From an overhead point of view i think it is not optimal, for example for a large string it could be much faster to have it changed in place, not generating a new one for every step in a change. For strings, the following points apply; as a net result, the overhead is *less* than it would be if strings were mutable: - strings must be hashable, so they can be used as a dictionary key. If you would modify, say, len.func_name, then newly imported code could not find the len function anymore. It would be possible to solve this by introducing an additional immutable identifier type, but then you would need to create copies of strings (to create identifier object). Many applications might break which currently use strings as dictionary keys. - strings are currently assumed to be shareable. You pass strings to functions which then store the strings in global variables, object attributes, etc. In all these places, copies would need to be made if strings were mutable, since the caller might chose to modify the string afterwards. - immutable strings consume less memory than mutable strings would, because a string is made up of just one memory block. Regards, Martin -- http://mail.python.org/mailman/listinfo/python-list
Weekly Python Patch/Bug Summary
Patch / Bug Summary
___
Patches : 272 open ( +5) / 2737 closed (+10) / 3009 total (+15)
Bugs: 793 open ( -5) / 4777 closed (+29) / 5570 total (+24)
RFE : 165 open ( +0) / 141 closed ( +1) / 306 total ( +1)
New / Reopened Patches
__
Enhance tracebacks and stack traces with vars (2005-01-08)
http://python.org/sf/1098732 opened by Skip Montanaro
Single-line option to pygettext.py (2005-01-09)
http://python.org/sf/1098749 opened by Martin Blais
improved smtp connect debugging (2005-01-11)
CLOSED http://python.org/sf/1100140 opened by Wummel
Log gc times when DEBUG_STATS set (2005-01-11)
http://python.org/sf/1100294 opened by Skip Montanaro
deepcopying listlike and dictlike objects (2005-01-12)
http://python.org/sf/1100562 opened by Björn Lindqvist
ast-branch: fix for coredump from new import grammar (2005-01-11)
http://python.org/sf/1100563 opened by logistix
datetime.strptime constructor added (2005-01-12)
http://python.org/sf/1100942 opened by Josh
Feed style codec API (2005-01-12)
http://python.org/sf/1101097 opened by Walter Dörwald
Patch for potential buffer overrun in tokenizer.c (2005-01-13)
http://python.org/sf/1101726 opened by Greg Chapman
ast-branch: hacks so asdl_c.py generates compilable code (2005-01-14)
http://python.org/sf/1102710 opened by logistix
Fix for 926423: socket timeouts + Ctrl-C don't play nice (2005-01-15)
http://python.org/sf/1102879 opened by Irmen de Jong
Boxing up PyDECREF correctly (2005-01-15)
CLOSED http://python.org/sf/1103046 opened by Norbert Nemec
AF_NETLINK sockets basic support (2005-01-15)
http://python.org/sf/1103116 opened by Philippe Biondi
Adding the missing socket.recvall() method (2005-01-16)
http://python.org/sf/1103213 opened by Irmen de Jong
tarfile.py: fix for bug #1100429 (2005-01-16)
http://python.org/sf/1103407 opened by Lars Gustäbel
Patches Closed
__
pydoc data descriptor unification (2004-04-17)
http://python.org/sf/936774 closed by jlgijsbers
xml.dom missing API docs (bugs 1010196, 1013525) (2004-10-21)
http://python.org/sf/1051321 closed by jlgijsbers
Fix for bug 1017546 (2004-08-27)
http://python.org/sf/1017550 closed by jlgijsbers
fixes urllib2 digest to allow arbitrary methods (2005-01-04)
http://python.org/sf/1095362 closed by jlgijsbers
Bug fix 548176: urlparse('http://foo?blah') errs (2003-03-30)
http://python.org/sf/712317 closed by jlgijsbers
bug fix 702858: deepcopying reflexive objects (2003-03-22)
http://python.org/sf/707900 closed by jlgijsbers
minor codeop fixes (2003-05-15)
http://python.org/sf/737999 closed by jlgijsbers
SimpleHTTPServer reports wrong content-length for text files (2003-11-10)
http://python.org/sf/839496 closed by jlgijsbers
improved smtp connect debugging (2005-01-11)
http://python.org/sf/1100140 closed by jlgijsbers
Boxing up PyDECREF correctly (2005-01-15)
http://python.org/sf/1103046 closed by rhettinger
New / Reopened Bugs
___
socket.setdefaulttimeout() breaks smtplib.starttls() (2005-01-08)
http://python.org/sf/1098618 opened by Matthew Cowles
set objects cannot be marshalled (2005-01-09)
CLOSED http://python.org/sf/1098985 opened by Gregory H. Ball
codec readline() splits lines apart (2005-01-09)
CLOSED http://python.org/sf/1098990 opened by Irmen de Jong
Optik OptionParse important undocumented option (2005-01-10)
http://python.org/sf/1099324 opened by ncouture
refman doesn't know about universal newlines (2005-01-10)
http://python.org/sf/1099363 opened by Jack Jansen
raw_input() displays wrong unicode prompt (2005-01-10)
http://python.org/sf/1099364 opened by Petr Prikryl
tempfile files not types.FileType (2005-01-10)
CLOSED http://python.org/sf/1099516 opened by Frans van Nieuwenhoven
copy.deepcopy barfs when copying a class derived from dict (2005-01-10)
http://python.org/sf/1099746 opened by Doug Winter
Cross-site scripting on BaseHTTPServer (2005-01-11)
http://python.org/sf/1100201 opened by Paul Johnston
Scripts started with CGIHTTPServer: missing cgi environment (2005-01-11)
http://python.org/sf/1100235 opened by pacote
Frame does not receive configure event on move (2005-01-11)
http://python.org/sf/1100366 opened by Anand Kameswaran
Wrong "type()" syntax in docs (2005-01-11)
http://python.org/sf/1100368 opened by Facundo Batista
TarFile iteration can break (on Windows) if file has links (2005-01-11)
http://python.org/sf/1100429 opened by Greg Chapman
Python Interpreter shell is crashed (2005-01-12)
http://python.org/sf/1100673 opened by abhishek
test_fcntl fails on netbsd2 (2005-01-12)
http://python.org/sf/1101233 opened
Re: Statement local namespaces summary (was Re: python3: 'where' keyword)
Nick Coghlan wrote:
# Anonymous functions
use res:
def f(x):
d = {}
exec x in d
return d
in:
res = [f(i) for i in executable]
as for me, I found construction "use :" unobvious and confusing.
Also there is great possibility to forget some of variables names.
I think that syntax
where:
is more obvious. (and we already have defined semantics for it)
we have two problems, that we try to solve
1) create method to nest scopes
2) create method to reverse execution order for better readability
"using:" solves both at once.
but your "use ... in ..." syntax shows, that you want to be able to
solve 1) independently i.e. create nested scope without reversing
execution order.
so, I can suggest one more keyword "do:", which will create nested
scope, just as "def f(): ... ; f()" do (and that could be just syntaxic
sugar for it.
so "use ... in ..." would look the following way:
do:
res = [f(i) for i in executable]
#some more equations here
using:
def f(x):
d = {}
exec x in d
return d
that seems good for me. of course if you want to return something from
the nest scope you must show that variable is from parent scope.
// while writing that I realized that it's too complex to be implemented
in python in that way. consider it as some type of brainstorming.
--
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Executing a script created by the end user
I am working on a python project where an object will have a script that can be edited by the end user: object.script If the script is a simple one with no functions, I can easily execute it using: exec object.script But if the object script is a bit more complicated, such as the example below, my approach does not work: def main(): hello1() hello2() def hello1(): print 'hello1' def hello2(): print 'hello2' -- http://mail.python.org/mailman/listinfo/python-list
Re: protecting the python code.
nell wrote: Hi Steve, First the "10x in advance" means thanks in advance. The main importance of protecting my code is to save headache of customers that want to be smart and change it and then complain on bugs and problems. 10x I'd say that's more of a policy issue than a technical issue. You have a contract or agreement with your customers, right? Just place a cluase in it that addresses your concerns. You don't have to support people who have altered your code... nor should they expect to be supported. -- http://mail.python.org/mailman/listinfo/python-list
Re: Newbie inheritance question.
On Sun, 16 Jan 2005 22:08:13 +0800, bwobbones wrote: > Hi all, > > I'm a java programmer struggling to come to terms with python - bear > with me! Christophe already identified the problem, I wanted to address another Javaism in your code, for your educational benefit. Speaking "idiomatically" (since this is all small sample code), in Python you'd normally code your driver as follows: -- import two t = two() # or something, there's a name conflict here, too many "two"s t.printHello() t.printTestVar() -- Things that aren't objects shouldn't be forced to be objects and I don't think there is any shame in having a non-OO top level. (I go on about this at http://www.jerf.org/writings/bowersLaw.html#4 in more detail.) -- http://mail.python.org/mailman/listinfo/python-list
Scriptomatic 2.0
Hi ! Scriptomatic 2.0 can, now, to generate scripts in Python. Download : http://www.microsoft.com/downloads/thankyou.aspx?FamilyID=09dfc342-648b-4119-b7eb-783b0f7d1178&displaylang=en Note : scriptomatic is a generator of WMI's scripts, for Windows, (and compatibles WBEM). Good night -- Michel Claveau -- http://mail.python.org/mailman/listinfo/python-list
List problems in C code ported to Python
I'm done porting the C code, but now when running the script I continually run into problems with lists. I tried appending and extending the lists, but with no avail. Any help is much appreciated Please see both the Python and C code at http://home.earthlink.net/~lvraab. The two files are ENIGMA.C and engima.py TIA -- http://mail.python.org/mailman/listinfo/python-list
Re: Newbie inheritance question.
bwobbones wrote: > Hi all, > > I'm a java programmer struggling to come to terms with python - bear > with me! > > I'm trying to subclass a class, and I want to be able to see it's > attributes also. Here are my classes: > > two.py > * > from one import one > > class two(one): > def __init__(self): > print "two" > > def printTestVar(self): > print "testVar: " + str(self.testVar) > * You simply forgot to call the parent __init__. You have to do that explicitely in Python. -- http://mail.python.org/mailman/listinfo/python-list
Re: List problems in C code ported to Python
On 2005-01-16, Lucas Raab <[EMAIL PROTECTED]> wrote: > I'm done porting the C code, but now when running the script I > continually run into problems with lists. I tried appending and > extending the lists, but with no avail. Any help is much appreciated > Please see both the Python and C code at > http://home.earthlink.net/~lvraab. The two files are ENIGMA.C and engima.py http://www.catb.org/~esr/faqs/smart-questions.html -- Grant Edwards grante Yow! Did an Italian CRANE at OPERATOR just experience visi.comuninhibited sensations in a MALIBU HOT TUB? -- http://mail.python.org/mailman/listinfo/python-list
Re: Why would I get a TypeEror?
På 14. jan 2005 kl. 22:58 skrev Steven Bethard: (Any mac users? How do I fix this to appear in Norwegian? =) Note that if you're not comfortable with short-circuiting behavior, you can also code this using lazy evaluation: (lambda: 1/x, lambda: 1.0e99)[x==0]() .. and people wonder why so many Python people want to get rid of Lambda =) -- Stian Søiland You can't say civilization don't Trondheim, Norway advance, however, for in every war http://www.soiland.no/ they kill you in a new way. [Rogers] =/\= -- http://mail.python.org/mailman/listinfo/python-list
[perl-python] 20050116 defining a function
© # the following is a example of defining
© # a function in Python.
©
© def fib(n):
© """This prints n terms of a sequence
© where each term is the sum of previous two,
© starting with terms 1 and 1."""
© result=[];a=1;b=1
© for i in range(n):
© result.append(b)
© a,b=b,a+b;
© result.insert(0,1)
© del result[-1]
© return result
©
© print fib(6)
©
© # note the use of .insert to insert 1 at
© # the beginning of a list, and Òdel
© # result[-1]Ó to remove the last element
© # in a list. Also, the string
© # immediately following the function
© # definition is the function's
© # documentation.
©
© # the unusual syntax of a.insert() is
© # what's known as Object Oriented syntax style.
©
© # try writing a factorial function.
©
© ---
© # the equivalent perl version is this:
©
© =pod
©
© fib(n) prints n terms of a sequence where each
© term is the sum of previous two,
© starting with terms 1 and 1.
©
© =cut
©
© use strict;
© my @result;
© my ($a, $b);
©
© sub fib($) {
© my $n= @_[0];
© @result=();$a=1;$b=1;
© for my $i (1..$n){
© push @result, $b;
© ($a,$b)=($b,$a+$b);
© }
© unshift @result, 1;
© pop @result;
© return @result;
© }
©
© use Data::Dumper;
© print Dumper [fib(5)];
©
© # the =pod and =cut
© # is perl's way of demarking inline
© # documentation called POD.
© # see Òperldoc -t perlpodÓ
© # note: the empty line around it
© # is necessary, at least in perl version
© # 5.6 up to ~2002.
©
© # the Òuse strict;Ó is to make perl's
© # loose syntax stricter by enforcement.
© # Its use is encouraged by
© # perl gurus, but not all standard
© # packages use it.
©
© # the ÒmyÓ are used to declare variables.
© # necessary under Òuse strict;Ó
© # see Òperldoc -t strictÓ
©
© # the $ in fib($) is there to declare
© # that fib has a parameter of one scalar.
© # Its use is however optional and uncommon.
© # it is used for clarity but
© # has also met with controversy by
© # perl gurus as being unperl.
© # see Òperldoc perlsubÓ for ref.
©
© # the @_[0] is the first element of the
© # array @_. The @_ array is a predefined
© # array, holding arguments to subroutines.
© # see Òperldoc -t perlvarÒ
©
© # see
© # perldoc -tf unshift
© # perldoc -tf pop
©
© # the last line, [fib(5)], is basically
© # to make it a memory address of a copy of
© # the list returned by fib(5), so that
© # Dumper can print it.
© # see Òperldoc -t perldataÓ or perlref
© # for unix-styled technicalities.
©
© Xah
© [EMAIL PROTECTED]
© http://xahlee.org/PageTwo_dir/more.html
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Re: why are some types immutable?
Torsten Mohr <[EMAIL PROTECTED]> wrote: > reading the documentation (and also from a hint from this NG) > i know now that there are some types that are not mutable. > > But why is it this way? > > From an overhead point of view i think it is not optimal, > for example for a large string it could be much faster to > have it changed in place, not generating a new one for > every step in a change. There has been a huge amount written about immutable types recently. A search of the Google news archives should turn up tons of articles. But, in a nutshell, the biggest reason for immutable types (tuples and strings) is that this lets they be dictionary keys. If you want to know why dictionary keys have to be immutable, do that google search; there was a huge thread on exactly that subject just in the path month or two. Making strings immutable has some good points (in addition to making them usable as dictionary keys) and bad points. On the good side, it lets you intern strings and share memory. For example: >>> a = "fred" >>> b = "fred" >>> id (a) 3587520 >>> id (b) 3587520 when the interpreter saw the string "fred" in the second assignment statement, it looked it up and discovered that it already had a string with the value "fred", so it just re-used the same string (which is why they both have the same id). This saves memory (which can become important when you have a lot of strings). It also makes string comparison more efficient, since a test for equality can often be satisfied by just comparing id's. The bad side is that, as you mentioned, things like: s = "" for c in getCharacters(): s = s + c become very inefficient: O(n^2). Fortunately, there is an easy idiom to avoid that quadratic behavior. You just accumulate the characters in a list, O(n), and then convert the list to a string with join(), also O(n). Two O(n) passes is a heck of a lot better than a single O(n^2). l = [] for c in getCharacters(): l.append (c) s = "".join (l) Other types of in-place string manipulation could use the same trick. -- http://mail.python.org/mailman/listinfo/python-list
Re: generator expressions: performance anomaly?
On Sun, 16 Jan 2005 12:18:23 GMT, "Raymond Hettinger"
<[EMAIL PROTECTED]> wrote:
>"John Machin" <[EMAIL PROTECTED]> wrote in message
>news:[EMAIL PROTECTED]
>> Please consider the timings below, where a generator expression starts
>> out slower than the equivalent list comprehension, and gets worse:
>>
>> >python -m timeit -s "orig=range(10)" "lst=orig[:];lst[:]=(x for x
>> in orig)"
> . . .
>> >python -m timeit -s "orig=range(20)" "lst=orig[:];lst[:]=(x for x
>> in orig)"
>
>This has nothing to do with genexps and everything to do with list slice
>assignment.
>
>List slice assignment is an example of a tool with a special case optimization
>for inputs that know their own length -- that enables the tool to pre-allocate
>its result rather than growing and resizing in spurts. Other such tools
>include
>tuple(), map() and zip().
>
My reading of the source: if the input is not a list or tuple, a
(temporary) tuple is built from the input, using PySequence_Tuple() in
abstract.c. If the input cannot report its own length, then that
function resorts to "growing and resizing in spurts", using the
following code:
if (j >= n) {
if (n < 500)
n += 10;
else
n += 100;
if (_PyTuple_Resize(&result, n) != 0) {
Perhaps it could be changed to use a proportional increase, like
list_resize() in listobject.c, which advertises (amortised) linear
time. Alternative: build a temporary list instead?
--
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Re: threading and sockets ?
ionel wrote: how to make a efficient server.. please point me to some good and clear examples I nominate SocketServer.ThreadingTCPServer from the standard library. --Irmen -- http://mail.python.org/mailman/listinfo/python-list
Re: generator expressions: performance anomaly?
Nick Coghlan: >There's a similar performance glitch associated with constructing a tuple from a generator expression (with vanilla 2.4, detouring via list is actually faster) You look right: .from time import clock .print "[x for x in l], list(x for x in l), aux = list(x for x in l); tuple(aux), tuple(x for x in l):" .for np in range(13, 21): .n = 1*2**np .print "n:", n, " s:", .l = xrange(n) .t1 = clock() .[x for x in l] .t2 = clock() .print round(t2-t1,3), . .t1 = clock() .list(x for x in l) .t2 = clock() .print round(t2-t1,3), . .t1 = clock() .aux = list(x for x in l) .tuple(aux) .t2 = clock() .print round(t2-t1,3), . .#l = tuple(l) useless .t1 = clock() .tuple(x for x in l) .t2 = clock() .print round(t2-t1,3) Output: [x for x in l], list(x for x in l), aux = list(x for x in l); tuple(aux), tuple(x for x in l): n: 8192 s: 0.01 0.007 0.01 0.013 n: 16384 s: 0.024 0.019 0.021 0.032 n: 32768 s: 0.054 0.042 0.049 0.113 n: 65536 s: 0.111 0.078 0.101 0.088 n: 131072 s: 0.196 0.155 0.183 0.177 n: 262144 s: 0.436 0.385 0.429 1.832 n: 524288 s: 0.921 0.744 0.877 8.271 n: 1048576 s: 1.86 1.546 1.866 33.154 The timings for tuple(x for x in l) seem to grow as len(n)**2. Bear hugs, Bearophile -- http://mail.python.org/mailman/listinfo/python-list
Re: generator expressions: performance anomaly?
[Raymond Hettinger]
> >List slice assignment is an example of a tool with a special case
optimization
> >for inputs that know their own length -- that enables the tool to
pre-allocate
> >its result rather than growing and resizing in spurts. Other such tools
include
> >tuple(), map() and zip().
[John Machin]
> My reading of the source: if the input is not a list or tuple, a
> (temporary) tuple is built from the input, using PySequence_Tuple() in
> abstract.c. If the input cannot report its own length, then that
> function resorts to "growing and resizing in spurts", using the
> following code:
>
> if (j >= n) {
> if (n < 500)
> n += 10;
> else
> n += 100;
> if (_PyTuple_Resize(&result, n) != 0) {
>
> Perhaps it could be changed to use a proportional increase, like
> list_resize() in listobject.c, which advertises (amortised) linear
> time.
Check out the current source. The time machine beat you to it.
Keep the faith,
Raymond Hettinger
--
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RE: generator expressions: performance anomaly?
Raymond Hettinger wrote: > Check out the current source. The time machine beat you to it. Nick's other suggestion - that genexps propagate __len__ - might still be interesting. Of course, it would only be applicable for unconditional genexps(i.e. no if clause). Tim Delaney -- http://mail.python.org/mailman/listinfo/python-list
Re: Integration with java (Jpype vs. JPE)
Cameron Laird wrote: In article <[EMAIL PROTECTED]>, Jon Perez <[EMAIL PROTECTED]> wrote: Can someone summarize in a nutshell what is the difference between JPype and JPE? JPE's the original. It provided more functionality than JPype has achieved so far, I believe (though that could change any day). I think no one now maintains JPE. Someone really ought to include a couple of sentences to that effect on the front page of http://jpype.sf.net/ >. Well, Cameron summed it up pretty good :) I'd add that The only major (and yes I know it is VERY major) funtionailty missing in JPype is the ability to subclass Java classes in Python. On the other hand JPype will (soon) have functionality that JPE doesnt have. Java arrays can already (in 0.4) be iterated as regular Python collections. Version 0.5 will add that same behavior for Java collections (Map, List, Set, Iterator). Of course, the above is based on the JPE documentation, because I havent been able to get JPE to work. About Cameron's suggestion, sure. I'll do it as soon as I (or someone else) can get both JPype and JPE to work so they can be compared through more than just their respective documentation. Steve a.k.a devilwolf on sourceforge -- http://mail.python.org/mailman/listinfo/python-list
Re: protecting the python code.
Hi Steve, First the "10x in advance" means thanks in advance. The main importance of protecting my code is to save headache of customers that want to be smart and change it and then complain on bugs and problems. 10x -- http://mail.python.org/mailman/listinfo/python-list
Re: Why would I get a TypeEror?
Stian Soiland wrote: På 14. jan 2005 kl. 22:58 skrev Steven Bethard: (Any mac users? How do I fix this to appear in Norwegian? =) Note that if you're not comfortable with short-circuiting behavior, you can also code this using lazy evaluation: (lambda: 1/x, lambda: 1.0e99)[x==0]() .. and people wonder why so many Python people want to get rid of Lambda =) Heh heh. No I don't. ;) In fact, I don't ever use lambdas in any of my own "real" code. But I don't mind being a little dirty when I post to c.l.py. ;) I guess I could have written this as: def inverse(): return 1/x def largenum(): return 1.0e99 b = (inverse, largenum)[x==0]() but I'm usually too lazy, and it's an ugly solution anyway, compared to the simple one which the OP was apparently trying to avoid: if x != 0: b = 1/x else: b = 1.0e99 =) Steve -- http://mail.python.org/mailman/listinfo/python-list
Re: pygame + py2exe = bad exe. why?
M.E.Farmer wrote:
>
> Erik glad to see you were able to track it down.
> Have you been succesful in making the changes they mentioned?
> M.E.Farmer
Yes below is a simple script that works. The key was that pygame uses
freesansbold.ttf as the default font and that is not copied over in the
normal py2exe process. See the end of the setup script.
#!/usr/bin/env python
from distutils.core import setup
import py2exe, pygame
import glob, shutil
setup(windows=["mahjong.py"],
name='GoPets Mahjong',
version='0.3.1',
description='Mahjong for GoPets Users',
author='Erik Bethke',
author_email='[EMAIL PROTECTED]',
url='www.erikbethke.com',
py_modules=['mahjong','background','board','tile','textBox']
)
shutil.copytree('data', 'dist/data')
shutil.copyfile('freesansbold.ttf', 'dist/freesansbold.ttf')
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Re: nntplib: abstraction of threads
Rakesh schrieb:
> What I want is to *group the messages belonging to each thread* .
Hello
Why not sort with Message-ID and References?
Attention - it is a Newbie-Solution.
import nntplib
hamster = nntplib.NNTP('127.0.0.1', 119, 'user', 'pass')
resp, count, first, last, name = hamster.group('comp.lang.python')
resp, items = hamster.xover(first,last)
start_dic = {}
re_dic = {}
numb = 1
for id,subject,author,date,message_id,references,size,lines in items:
if 'Re:' not in subject:
start_dic[subject] = (author, message_id)
else:
re_dic[numb] = (subject, author, references)
numb += 1
resp = hamster.quit()
for a in start_dic:
print a
print start_dic[a][0]
for b in re_dic:
if start_dic[a][1] in re_dic[b][2]:
print '|'
print ' ->', re_dic[b][0]
print ' ', re_dic[b][1]
print
--
Werner Amann
--
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Re: nntplib: abstraction of threads
Werner Amann wrote:
Rakesh schrieb:
What I want is to *group the messages belonging to each thread* .
Hello
Why not sort with Message-ID and References?
Attention - it is a Newbie-Solution.
import nntplib
hamster = nntplib.NNTP('127.0.0.1', 119, 'user', 'pass')
resp, count, first, last, name = hamster.group('comp.lang.python')
resp, items = hamster.xover(first,last)
start_dic = {}
re_dic = {}
numb = 1
for id,subject,author,date,message_id,references,size,lines in items:
if 'Re:' not in subject:
start_dic[subject] = (author, message_id)
else:
re_dic[numb] = (subject, author, references)
numb += 1
resp = hamster.quit()
for a in start_dic:
print a
print start_dic[a][0]
for b in re_dic:
if start_dic[a][1] in re_dic[b][2]:
print '|'
print ' ->', re_dic[b][0]
print ' ', re_dic[b][1]
print
Better still, do a Google search on "mail threading algorithm",
implement the algorithm described in
http://www.jwz.org/doc/threading.html
and post your implementation back to the newsgroup :-)
regards
Steve
--
Steve Holden http://www.holdenweb.com/
Python Web Programming http://pydish.holdenweb.com/
Holden Web LLC +1 703 861 4237 +1 800 494 3119
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Re: why are some types immutable?
Roy Smith wrote: > Torsten Mohr <[EMAIL PROTECTED]> wrote: > > reading the documentation (and also from a hint from this NG) > > i know now that there are some types that are not mutable. > > > > But why is it this way? > > > > From an overhead point of view i think it is not optimal, > > for example for a large string it could be much faster to > > have it changed in place, not generating a new one for > > every step in a change. > > There has been a huge amount written about immutable types recently. A > search of the Google news archives should turn up tons of articles. > > But, in a nutshell, the biggest reason for immutable types (tuples and > strings) is that this lets they be dictionary keys. If you want to know > why dictionary keys have to be immutable, More precisely, dictionary keys can't be mutable in any way that affects the result of the hash function or the == or != operators. -- http://mail.python.org/mailman/listinfo/python-list
Re: protecting the python code.
nell wrote:
Hi Steve,
First the "10x in advance" means thanks in advance.
The main importance of protecting my code is to save headache of
customers that want to be smart and change it and then complain on bugs
and problems.
10x
I'd have understood "tnx", never seens 10x b4 :-)
Your concerns are what licensing's for. ("No support on modified copies"
would be a good heading for a section addressing this issue).
With good enough release controls you can verify the code is unmodified
using md5 checksums or similar.
If a customer's good enough at Python to disassemble your .pyc files,
they will probably tell you they've modified your code when the support
queries come in :-)
regards
Steve
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Re: why are some types immutable?
In article <[EMAIL PROTECTED]>, "Dan Bishop" <[EMAIL PROTECTED]> wrote: > Roy Smith wrote: > > Torsten Mohr <[EMAIL PROTECTED]> wrote: > > > reading the documentation (and also from a hint from this NG) > > > i know now that there are some types that are not mutable. > > > > > > But why is it this way? > > > > > > From an overhead point of view i think it is not optimal, > > > for example for a large string it could be much faster to > > > have it changed in place, not generating a new one for > > > every step in a change. > > > > There has been a huge amount written about immutable types recently. > A > > search of the Google news archives should turn up tons of articles. > > > > But, in a nutshell, the biggest reason for immutable types (tuples > and > > strings) is that this lets they be dictionary keys. If you want to > know > > why dictionary keys have to be immutable, > > More precisely, dictionary keys can't be mutable in any way that > affects the result of the hash function or the == or != operators. Yes, this is true. In fact, I spent a fair amount of time in the referenced thread arguing exactly that point. I was hoping people would take my hint, read the thread, and find that out :-) -- http://mail.python.org/mailman/listinfo/python-list
PythonMagick Update
Hi, I'm working on a new version of PythonMagick, a wrapper for GraphicsMagick. A first version is available at: http://public.procoders.net/cgi-bin/trac.cgi/wiki/PythonMagick Any feedback is very appreciated. regards, Achim -- http://mail.python.org/mailman/listinfo/python-list
Re: Checking for X availability
In article <[EMAIL PROTECTED]>, Nils Nordman <[EMAIL PROTECTED]> wrote: >On Tue, Jan 11, 2005 at 03:32:01AM -0800, Flavio codeco coelho wrote: >> So my question is: how can I check for the availability of X? i.e., >> How will my program know if its running in a text only console or in >> console window over X? > >Well, one way to do it is to check whether the environment variable >DISPLAY is set (which it is when running under X, and should not be >otherwise). . . . While there certainly are successful programs that use this approach, it's NOT true in general--at least in the generality I encounter. It can happen, for example, that a user withOUT $DISPLAY in the environment launches interesting_application -display SOME_DISPLAY ... Jeremy Bowers gives excellent advice elsewhere in this thread: try, and use exceptions to learn what's going on; as you learn more, relaunch the application with a refined command-line. -- http://mail.python.org/mailman/listinfo/python-list
Re: PyChecker messages
In article <[EMAIL PROTECTED]>, Roger Binns <[EMAIL PROTECTED]> wrote: . . . >> runner.py:200: Function (detectMimeType) has too many returns (11) >> >> The function is simply a long "else-if" clause, branching out to different >> return statements. What's wrong? It's simply a "probably ugly code" advice? > >That is also advice. Generally you use a dict of functions, or some other >structure to lookup what you want to do. . . . This interests me. Let's be more precise. Use, it's absolutely true that good Python style exploits dicts far more than newcomers realize (although somewhat less than Lua, a language which intriguingly pushes dictionary pragmatics to the limit). In particular, it is frequently the case that beginners' appetite for a "switch" is best met by a lesson in use of a dictionary of functions. HOWEVER, proliferation of functions itself adds weight. My own counsel is that a simple sequence of if ... return ... if ... return ... often is exactly the right definition for a specific function. I, incidentally, prefer this form over the if ... return ... elif ... return ... the original poster described. So: yes, "[g]enerally you use a dict of functions" when PyChecker thinks you have "too many returns", but I do NOT advise it for the specific case that appears to be at hand. -- http://mail.python.org/mailman/listinfo/python-list
Re: Newbie: module structure and import question
> yes i know it's related to search path, but i don't know how to set it in a > practical way (beside hard coding). > my concern is, if i want to create a custom module/library, i don't know > what py file will import it and where the working directory should be. Regarding where the current working directory is -- on Linux your right, you probably don't know where it is going to be. On Windows -- you can pretty much demand that users set up the launcher so that your python program is opened in a specific location -- typically the root directory of the installed package. So in the windows situation -- if all your components are in that package directory you can access everything via relative roots. Linux is not so easy -- I'll get to that. On the other hand, if your installing a general directory library module that your going to use from a variety of other programs, then you need to have the installer setup things so other applications can find it. The standard way to do this is to use the distutils package that is part of the python distribution to install these modules in a standard location which should already be in the search path. If you don't want to do that you have to do something special: on windows create a registry entry that can be accessed and looked up probably, or setup the default python path for your system (or user) to include the extra directories, or like GNOME does on Linux -- create a script in the executable search path that your program or installer can run -- and have it return the path you need. So on the application side, you'd find out the location of the library as described above and set sys.path. You can either do this at launch time in your main program -- or you can have the installer hard code it at the top of the main program. This is not really any different then for example using shared libraries. You either need to install all of your modules in the search path to start with or you need to modify the search path by some method. There is one more thought -- if you want to find out where the python module is in the file system -- there are sometimes ways to do this -- I've never done this but I have some notes somewhere about this. This might also be helpful in finding directories for example. If your interested in this -- maybe someone else here can remember? > But if i put a set of classes in a py file as a module, will it increase > the dependency of each class? > back to my example, of course, i can put BaseA and ClassA together in one py > file. what should i do when i need to add one more class later, "ClassB", > which also extend BaseA. Put it into the same file or in a new file? if put > in in the same file, i think it should difficult to maintain versioning. Versioning -- hmm. Well I think it depends. If ClassB is intended to be a general capability that you want to add to to moduleA (the module with BaseA and ClassA), then add it to moduleA but make the module upwardly compatible. If you want to track versions, then just keep old version snapshots if you need to or use something like CVS to do it for you. I'm pretty basic so I keep old copies but try to make my general libraries upwardly compatible if possible. Of course on the other hand, if the new class classB has a special function then I'd either create a new module, or I'd just include it into my main program module, or some other application module. To merge the functions just import what you need into that module. I for example often use "from mymodule import *" which imports everything rather than the limited imports you used -- nothing wrong with either, just a matter of taste. I also often use "import" and write the full module name when I reference things too. The point is -- I personally think one should look at modules as being collections of functions, classes, and other constructs that form librararies rather than putting each class and function in a separate module. Thanks, Rob -- http://mail.python.org/mailman/listinfo/python-list
Re: List problems in C code ported to Python
Lucas Raab wrote: Please see both the Python and C code at http://home.earthlink.net/~lvraab. The two files are ENIGMA.C and engima.py If you post a small testcase here you are much more likely to get helped. -- Michael Hoffman -- http://mail.python.org/mailman/listinfo/python-list
Re: why are some types immutable?
Torsten Mohr schrieb:
reading the documentation (and also from a hint from this NG)
i know now that there are some types that are not mutable.
But why is it this way?
Immutable types (e.g. strings, tuples) allow for code optimization
in some situations and can be used as dictionary keys. For the latter
reason see:
http://www.python.org/moin/DictionaryKeys
--
---
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E-mail 'cGV0ZXIubWFhc0BtcGx1c3IuZGU=\n'.decode('base64')
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Re: How to del item of a list in loop?
skull wrote: > According to Nick's article, I added three 'reversed' methods to your provided > test prog. and the result turned out method_reversed is faster than others except the 'three' case. > Following is my modified version: [snip] > def method_reversed_idx(lst): > idx = 0 > for i in reversed(lst): > if i == 2: > del lst[idx] > idx += 1 There appears to be a problem with this one: >>> def method_reversed_idx(lst): ... idx = 0 ... for i in reversed(lst): ... if i == 2: ... del lst[idx] ... idx += 1 ... >>> lst=[1,2,3];method_reversed_idx(lst);print lst [1, 3] >>> lst=[2,1,3];method_reversed_idx(lst);print lst [2, 1] >>> lst=[1,3,2];method_reversed_idx(lst);print lst [3] >>> -- http://mail.python.org/mailman/listinfo/python-list
Re: Executing a script created by the end user
Craig Howard wrote:
I am working on a python project where an object will have a script that
can be edited by the end user: object.script
If the script is a simple one with no functions, I can easily execute it
using:
exec object.script
But if the object script is a bit more complicated, such as the example
below, my approach does not work:
def main():
hello1()
hello2()
def hello1():
print 'hello1'
def hello2():
print 'hello2'
What do you want to do if you get a script like this? Run main? You
could do something like:
py> s = """
... def main():
... hello1()
... hello2()
...
... def hello1():
... print 'hello1'
...
... def hello2():
... print 'hello2'
... """
py> d = {}
py> exec s in d
py> d["main"]()
hello1
hello2
(Actually, you don't need to exec it in d, that's probably just good
practice.)
Steve
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Re: import problems *newbie*
Thanks for your help Steve and F. Petitjean. Sorry for taking so long to get back, I was away from my lab for a few days. The path to my directory was not included in the sys.path list. Adding a my.pth file to the site-packages directory fixed the import problem. F. Petitjean, I originally edited the PYTHONPATH because "Learning Python," the O'Reilly book, says to do so. I like your and Steve's solutions better--editing the PYTHONPATH seems a little unwieldy--but just to satisfy my curiosity, what are some of the reasons these methods are preferable? Steve, as far as finding out the cause of this problem, I muddled around python and the registry for a while, but nothing jumped out at me. The only thing I can think of is that I have both Python 2.3 and 2.4 installed, and I'm currently working in 2.3. I thought that PYTHONPATH was an environment variable, so having two different versions wouldn't affect it, but I was wondering...should I bother uninstalling 2.4 to see if the prob gets fixed? Other than that I'm still something of a newbie, but I'd love to actually help fix this bug if you can think of anything for me to try (oh joy, my first open source contribution!). Thanks. ~mike -- http://mail.python.org/mailman/listinfo/python-list
Re: Excel module for Python
Simon Brunning <[EMAIL PROTECTED]> writes: > On Wed, 12 Jan 2005 23:19:44 +0800, sam <[EMAIL PROTECTED]> wrote: >> >> No, I don't use MS windows. I need to generate Excel file by printing >> data to it, just like Perl module Spreadsheet::WriteExcel. > If you need to write out formulae, formratting, that kind of thing, > then I think you'll need to write a 'real' Excel file. I don't have a > clue how to do that - sorry. There's actually an ancient open spreadsheet format called SYLK which is a step above CSV: it allows formatting of data, formulas etc. Google for SYLK to get the rather sparse specification (and skip over the first few links!) If you want to generate "real" Office files from UNIX, another alternative is to automate OpenOffice (which has a COM-like interface too) or generate OO XML files and feed them to OO asking to conver them with a bit of OO macro magic. -- === <[EMAIL PROTECTED]>Herlev, Denmark http://www.andreasen.org/> <*> === -- http://mail.python.org/mailman/listinfo/python-list
Re: List problems in C code ported to Python
Grant Edwards wrote: On 2005-01-16, Lucas Raab <[EMAIL PROTECTED]> wrote: I'm done porting the C code, but now when running the script I continually run into problems with lists. I tried appending and extending the lists, but with no avail. Any help is much appreciated Please see both the Python and C code at http://home.earthlink.net/~lvraab. The two files are ENIGMA.C and engima.py http://www.catb.org/~esr/faqs/smart-questions.html I didn't expect to get bitched out just because I didn't follow "protocol." -- http://mail.python.org/mailman/listinfo/python-list
Re: List problems in C code ported to Python
"Lucas Raab" <[EMAIL PROTECTED]> wrote in message
news:[EMAIL PROTECTED]
> I'm done porting the C code, but now when running the script I
> continually run into problems with lists. I tried appending and
> extending the lists, but with no avail. Any help is much appreciated
> Please see both the Python and C code at
> http://home.earthlink.net/~lvraab. The two files are ENIGMA.C and
engima.py
>
> TIA
I didn't actually run your script, but you have some fundamental things to
fix first. Here are some corrections that will get you closer:
- Single-character strings are still strings as far as Python is concerned.
Unlike C's distinction of single quotes for single characters (which allow
you to do integer arithmetic) and double quotes for string literals (which
don't support integer arithmetic), Python uses either quoting style for
strings. So "A" == 'a' is true in Python, not true in C. To do single-char
arithmetic, you'll need the ord() and asc() functions, so that instead of
c-'A'
you'll need
ord(c)-ord('A')
(and another little tip - since the ord('A') is likely to be invariant, and
used *heavily* in a function such as an Enigma simulator, you're best off
evaluating it once and stuffing it into a global, with an unimaginitive name
like ord_A = ord('A')
-Line 42: You are testing c == string.alpha_letters, when I think you
*really* want to test c in string.alpha_letters.
- encipher_file - the C version of this actually reads the file and calls
encipher() with each character in it. Your Python version just calls
encipher() with the complete file contents, which is certain to fail.
(another tip - avoid variable names like 'file', 'string', 'list', 'dict',
etc. as these collide with global typenames - also, your variable naming is
pretty poor, using "file" to represent the filename, and "filename" to
represent the file contents - err???)
- usage() - print("blahblah \n") - the trailing \n is unnecessary unless you
want to double-space your text
Although you say you are "done porting the C code", you really have quite a
bit left to do yet. You should really try to port this code a step at a
time - open a file, read its contents, iterate through the contents, call a
method, etc. "Big-bang" porting like this is terribly inefficient!
-- Paul
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Re: List problems in C code ported to Python
"Paul McGuire" <[EMAIL PROTECTED]> wrote: > "A" == 'a' is true in Python, not true in C. It could be true in C, if the string is stored in very low memory :-) -- http://mail.python.org/mailman/listinfo/python-list
Re: List problems in C code ported to Python
Paul McGuire wrote: So "A" == 'a' is true in Python, not true in C. >>> "A" == 'a' False I think you meant: >>> "A" == "A" True -- Michael Hoffman -- http://mail.python.org/mailman/listinfo/python-list
Re: List problems in C code ported to Python
Paul McGuire wrote: So "A" == 'a' is true in Python, not true in C. It's not true in Python either. You probably meant to say: "a" == 'a' (lowercase a) --Irmen -- http://mail.python.org/mailman/listinfo/python-list
Re: List problems in C code ported to Python
Lucas Raab wrote: Grant Edwards wrote: http://www.catb.org/~esr/faqs/smart-questions.html I didn't expect to get bitched out just because I didn't follow "protocol." I didn't see anyone bitch you out. And you were lucky that one person was kind enough to go through your web site and make some suggestions. If you had written a better question I guarantee you would have had more people answering your question sooner. Oh yeah, and: http://www.catb.org/~esr/faqs/smart-questions.html#not_losing -- Michael Hoffman -- http://mail.python.org/mailman/listinfo/python-list
Re: import problems *newbie*
In my experience (as a tester), it is easier to deal with PYTHONPATH than to add the my.pth file to the site-packages directory. The main reason is that I have my custom packages and modules in a directory tree that I deploy on many clients/servers/platforms/OS versions, some running different versions of Python. I found that I solve my import problems by adding one line to .bash_profile, which sets PYTHONPATH to the parent directory of my custom directory tree. Or, on Windows, I add an Environment variable, call it PYTHONPATH, and set it to the necessary directory. The alternative would be to hunt for the site-packages directory (of which there might be several) on all my systems. I guess it's a matter of taste in the end, but I do find the PYTHONPATH approach more suitable for automation and scripting, particularly when dealing with a large number of systems. Grig -- http://mail.python.org/mailman/listinfo/python-list
Re: List problems in C code ported to Python
Michael Hoffman wrote: Paul McGuire wrote: So "A" == 'a' is true in Python, not true in C. I think you meant: >>> "A" == "A" True Er, "A" == 'A' -- Michael Hoffman -- http://mail.python.org/mailman/listinfo/python-list
Re: python mode indentation problem
Xah Lee wrote: © ok, here's the ordeal. © © for i in range(5): © print i © for i in range(2): © print i, 'tt' © for i in [3]: © print i © for i in [32]: © print i © © # 1 level, 4 space © # 2 level, 1 tab © # 3 level, 1 tab, 4 spaces © # 4 level, 2 tabs. © © who the fuck coded the python mode in emacs? fuckhead please peruse: © http://xahlee.org/UnixResource_dir/writ/responsible_license.html I hope you never need a favor or interview for a job with someone who reads news groups. You're committing eSuicide by posting insulting rants such as this. All you accomplish is to isolate yourself. Try to be friendly. Ideas are only half the battle... presentation is the other half. You have some good and valid ideas, but your presentation is offensive and condescending. Your ideas are like golden coins wrapped in horse shit. Personally, I've had enough of your horse shit... perhaps I speak for others as well. -- http://mail.python.org/mailman/listinfo/python-list
Re: List problems in C code ported to Python
On 2005-01-16, Lucas Raab <[EMAIL PROTECTED]> wrote: >>>Please see both the Python and C code at >>>http://home.earthlink.net/~lvraab. The two files are ENIGMA.C >>>and engima.py >> >> http://www.catb.org/~esr/faqs/smart-questions.html > > I didn't expect to get bitched out just because I didn't > follow "protocol." You didn't get "bitched out". You did get some very sound advice. You want help solving a problem, and there are ways you can greatly increase the chances that you'll get help with your problem. After being told the best ways to get help, you whined about it rather than following it. Nobody owes you anything. Remember that. [You're darned lucky somebody did take the time to go to your web site and proof your code for you after your posting said in effect "I'm too lazy to compose and post a precise question, so go look at my program and fix it for me."] Now, go back and read the smart questions reference. -- Grant Edwards grante Yow! Hello? Enema at Bondage? I'm calling visi.combecause I want to be happy, I guess... -- http://mail.python.org/mailman/listinfo/python-list
Re: [perl-python] 20050115, for statement
Jeremy Bowers wrote: (Hell, five days into Python and some people are already producing working Backgammon games (I think that was the post last week), and Xah Lee here is still on for loops! Woo! Go Xah!) Mah Jongg, actually (if we're thinking of the same post), which name is often applied in the world of computer games to a what amounts to the old game of "Concentration" (rather than the real Mah Jongg which bears no more resemblance to the computerized version than Bridge bears to Go Fish). The player merely turns over cards/tiles two at a time and any identical pairs are removed. A backgammon game, with the computer actually playing against a human and all the logic that entails, would be much more sophisticated, and rather more work. ...not to diminish the impressiveness of someone new to Python building a visually attractive GUI application in only a few days and delivering it to the web which in several ways is far more than I've contributed in over five years. ;-) (Doffs hat to the former newbie who achieved this.) -Peter -- http://mail.python.org/mailman/listinfo/python-list
[perl-python] 20050117, filter, map
© # -*- coding: utf-8 -*-
© # Python
©
© # the "filter" function can be used to
© # reduce a list such that unwanted
© # elements are removed.
© # example:
©
© def even(n): return n % 2 == 0
© print filter( even, range(11))
©
©
© # the "map" function applies a function
© # to all elements of a list. Example:
©
© def square(n): return n*n
© print map(square, range(11))
©
©
© # similar perl versions
©
© use Data::Dumper;
© sub even {return $_[0]%2==0};
© print Dumper[ grep {even $_} (0..10)];
©
©
© # sub square {$n=shift;$n**2;};
© sub square {(shift)**2;};
© print Dumper [ map {square($_)} (0..10)];
©
© # the codes above showcase some syntax
© # variations commonly found in perl code
© # base
©
© -
©
© # in Mathematica for example, filter is
© # akin to Apply and map is MapThread.
© # The standard Map can be applied
© # according to a level spec of trees
© # and there's also MapAt, Nest,
© # NestList...any many more powerful
© # functions that manipulates trees.
© # lisp languages often have a subset
© # of it.
©
©
© Note: this post is from the Perl-Python
© a-day mailing list at
© http://groups.yahoo.com/group/perl-python/
© to subscribe, send an email to
© [EMAIL PROTECTED] if
© you are reading it on a web page,
© program examples may not run because
© html conversion often breaks the code.
©
© Xah
© [EMAIL PROTECTED]
© http://xahlee.org/PageTwo_dir/more.html
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Re: List problems in C code ported to Python
"Michael Hoffman" <[EMAIL PROTECTED]> wrote in message news:[EMAIL PROTECTED] > Michael Hoffman wrote: > > Paul McGuire wrote: > >> So "A" == 'a' is true in Python, not true in C. > > I think you meant: > > > > >>> "A" == "A" > > True > > Er, "A" == 'A' > -- > Michael Hoffman Yeah, that's the one I meant... :) -- Paul -- http://mail.python.org/mailman/listinfo/python-list
strange note in fcntl docs
In the fnctl docs for both python 2.3 and 2.4 there is a note at the bottom that says The os.open() function supports locking flags and is available on a wider variety of platforms than the lockf() and flock() functions, providing a more platform-independent file locking facility. however, in neither of those versions does os.open support any kind of mysterious "locking flags", nor is there any reference in os to any kind of locking magic (nor do any C open()s I know of support any kind of locking semantics). The note seems bogus; am I missing something, or should it be elided? -- John Lenton ([EMAIL PROTECTED]) -- Random fortune: Are Linux users lemmings collectively jumping off of the cliff of reliable, well-engineered commercial software? -- Matt Welsh signature.asc Description: Digital signature -- http://mail.python.org/mailman/listinfo/python-list
Re: [perl-python] 20050117, filter, map
Xah Lee wrote: © Note: this post is from the Perl-Python © a-day mailing list at © http://groups.yahoo.com/group/perl-python/ Is there any chance you could post these all as part of the same thread? That would be really nice for those of us who aren't interested -- then we could just ignore the thread... Thanks in advance, Steve -- http://mail.python.org/mailman/listinfo/python-list
fefinining % of c'm'y and k
hello i need a program (and pleas shoe me the modol in the softwar) that : if i have a scaned photo i want to define out of each poligon color ,as it seems in the photo, the cmyk in % (percets) of the color/ 4 exampl from poligon color orang defin the cmyk in % like that: (example) c: 30% m:56% y:78% k: 10% moshe thanks -- http://mail.python.org/mailman/listinfo/python-list
RE: fefinining % of c'm'y and k
[EMAIL PROTECTED] wrote: > hello > i need a program (and pleas shoe me the modol in the softwar) that : > if i have a scaned photo > i want to define out of each poligon color ,as it seems in the photo, > the cmyk > in % (percets) of the color/ > 4 exampl from poligon color orang defin the cmyk in % > like that: (example) > c: 30% > m:56% > y:78% > k: 10% This site will assist you greatly. http://www.catb.org/~esr/faqs/smart-questions.html Tim Delaney -- http://mail.python.org/mailman/listinfo/python-list
Re: [perl-python] 20050117, filter, map
Steven Bethard wrote: Is there any chance you could post these all as part of the same thread? That would be really nice for those of us who aren't interested -- then we could just ignore the thread... Or, better yet, not posting it at all. He's got his mailing list, what does he need to post it here for? -- Erik Max Francis && [EMAIL PROTECTED] && http://www.alcyone.com/max/ San Jose, CA, USA && 37 20 N 121 53 W && AIM erikmaxfrancis Make it come down / Like molasses rain -- Sandra St. Victor -- http://mail.python.org/mailman/listinfo/python-list
Re: fefinining % of c'm'y and k
On Sun, Jan 16, 2005 at 09:57:46PM -0800, [EMAIL PROTECTED] wrote:
> hello
> i need a program (and pleas shoe me the modol in the softwar) that :
> if i have a scaned photo
> i want to define out of each poligon color ,as it seems in the photo,
> the cmyk
> in % (percets) of the color/
> 4 exampl from poligon color orang defin the cmyk in %
> like that: (example)
> c: 30%
> m:56%
> y:78%
> k: 10%
> moshe
> thanks
if I understand you correctly, then what you want to do is to
determine the amounts of each color an image has. I can think of two
ways of doing this, both using PIL; one faster,
img = Image.open('foo.png')
dot = img.resize((1,1),1)
avg = dot.getpixel((0,0))
for i in zip(dot.getbands(), avg):
print "%s: %s" % i
and the other, thorougher
img = Image.open('foo.png')
width, height = img.size
numdots = width*height
avg = [sum(i)/numdots
for i in zip(*[img.getpixel((x,y))
for x in xrange(width)
for y in xrange(height)])]
for i in zip(dot.getbands(), avg):
print "%s: %s" % i
the first is usually pretty close to the second, but YMMV.
Converting from these image-specific average values to CMYK is a
non-trivial problem (impossible in the general casew); see for example
http://groups-beta.google.com/group/comp.lang.python/browse_thread/thread/2d0c54513c4970f7
where this issue was discussed.
--
John Lenton ([EMAIL PROTECTED]) -- Random fortune:
Excellent day to have a rotten day.
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Re: [perl-python] 20050116 defining a function
Xah Lee wrote: © my $n= @_[0]; Do you ever test your code before making fun of yourself in front of millions? *plonk* --Ala -- http://mail.python.org/mailman/listinfo/python-list
Re: video analysis with python
Hi Am 16.01.2005 12:44:27 schrieb Miki Tebeka: > 1. There is PyMedia (http://pymedia.org/) Is this library able to extract single images from a video? AFAICS it can only convert videos from one format to another. But I didn't try it, I've looked only in the docu. Maybe pyVideo (http://www.geocities.com/rtrocca/python/) would be a solution. But for me the AVIFile-Module doesn't work stable, it regularly crashes the python-interpreter. And there is a library for accessing DirectShow called PyDShowCam. cu boesi -- |¯|/¯/¯¯¯\|¯| |¯|¯| |¯|/¯/¯¯¯\|\|| #1671 : icq-intern http://| / / /¯\ | | | | | | / / /¯\ | (¯) | |¯¯#73628288 : icq-extern smb://| \ \ \_/ | `¯´ | |__| \ \ \_/ | ¯ /| ¯| boesi111 : aim ftp://|_|\_\___/|_|¯|_||_|\_\___/|_|¯¯ |_|¯ i171 : reallife -- http://mail.python.org/mailman/listinfo/python-list
pythonnt_rc_d.h is missed when building python from source ?
I download the source code of Python-2.3.4 from python.org. But I can't build python from source under Win2000. The compiler complained that there is no pythonnt_rc_d.h file which is included in Python-2.3.4\PC\python_nt.rc. Who knows the reason ? Thanks. Best Regards. Robert. -- http://mail.python.org/mailman/listinfo/python-list
Re: video analysis with python
On Mon, 17 Jan 2005 08:08:46 +0100, Alexander 'boesi' Bösecke <[EMAIL PROTECTED]> wrote: Hi Am 16.01.2005 12:44:27 schrieb Miki Tebeka: 1. There is PyMedia (http://pymedia.org/) Is this library able to extract single images from a video? AFAICS it can only convert videos from one format to another. But I didn't try it, I've looked only in the docu. Maybe pyVideo (http://www.geocities.com/rtrocca/python/) would be a solution. But for me the AVIFile-Module doesn't work stable, it regularly crashes the python-interpreter. And there is a library for accessing DirectShow called PyDShowCam. cu boesi I haven't tried it yet, but yes its pretty full featured library, there is a tutorial here on extracting images: http://java.sun.com/products/java-media/jmf/2.1.1/solutions/FrameAccess.html -- Ashot Petrosian University of Texas at Austin, Computer Sciences -- http://mail.python.org/mailman/listinfo/python-list
