On 11/14/2019 10:24 AM, James Lu wrote:
Where do I go to find a more complete specification for Python?
The Cpython code, the tests, and its actual behavior.
I want to
learn about common semi-internal language features used by popular
libraries, because I am reimplementing Python.
The refere
On 27 May 2015 at 19:00, Brian Blais wrote:
> On Mon, May 25, 2015 at 11:11 PM, Steven D'Aprano wrote:
>>
>> Let's compare three methods.
>>
>> def naive(a, b):
>> return math.sqrt(a**2 + b**2)
>>
>> def alternate(a, b):
>> a, b = min(a, b), max(a, b)
>> if a == 0: return b
>> if
On Mon, May 25, 2015 at 11:11 PM, Steven D'Aprano wrote:
>
> Let's compare three methods.
>
> def naive(a, b):
> return math.sqrt(a**2 + b**2)
>
> def alternate(a, b):
> a, b = min(a, b), max(a, b)
> if a == 0: return b
> if b == 0: return a
> return a * math.sqrt(1 + b**2 /
A minor point is that if you just need to compare distances you don't need to
compute the hypotenuse, its square will do so no subtractions etc etc.
--
Robin Becker
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On Tue, May 26, 2015, at 09:40, random...@fastmail.us wrote:
> On Mon, May 25, 2015, at 15:21, ravas wrote:
> > Is this valid? Does it apply to python?
> > Any other thoughts? :D
>
> The math.hypot function uses the C library's function which should deal
> with such concerns internally. There is a
On Mon, May 25, 2015, at 15:21, ravas wrote:
> Is this valid? Does it apply to python?
> Any other thoughts? :D
The math.hypot function uses the C library's function which should deal
with such concerns internally. There is a fallback version in case the C
library does not have this function, in P
On Monday, May 25, 2015 at 10:16:02 PM UTC-7, Gary Herron wrote:
> It's probably not the square root that's causing the inaccuracies. In
> many other cases, and probably here also, it's the summing of two
> numbers that have vastly different values that loses precision. A
> demonstration:
>
>
Am 26.05.15 um 05:11 schrieb Steven D'Aprano:
mismatch after 3 trials
naive: 767.3916150255787
alternate: 767.3916150255789
hypot: 767.3916150255787
which shows that:
(1) It's not hard to find mismatches;
(2) It's not obvious which of the three methods is more accurate.
The main problem is
On 05/25/2015 09:13 PM, ravas wrote:
On Monday, May 25, 2015 at 8:11:25 PM UTC-7, Steven D'Aprano wrote:
Let's compare three methods.
...
which shows that:
(1) It's not hard to find mismatches;
(2) It's not obvious which of the three methods is more accurate.
Thank you; that is very helpful!
Oh ya... true >_<
Thanks :D
On Monday, May 25, 2015 at 9:43:47 PM UTC-7, Ian wrote:
> > def distance(A, B):
> > """
> > A & B are objects with x and y attributes
> > :return: the distance between A and B
> > """
> > dx = B.x - A.x
> > dy = B.y - A.y
> > a = min(dx, dy)
On Mon, May 25, 2015 at 1:21 PM, ravas wrote:
> I read an interesting comment:
> """
> The coolest thing I've ever discovered about Pythagorean's Theorem is an
> alternate way to calculate it. If you write a program that uses the distance
> form c = sqrt(a^2 + b^2) you will suffer from the lose
On Monday, May 25, 2015 at 8:11:25 PM UTC-7, Steven D'Aprano wrote:
> Let's compare three methods.
> ...
> which shows that:
>
> (1) It's not hard to find mismatches;
> (2) It's not obvious which of the three methods is more accurate.
Thank you; that is very helpful!
I'm curious: what about the
On Tue, 26 May 2015 05:21 am, ravas wrote:
> I read an interesting comment:
> """
> The coolest thing I've ever discovered about Pythagorean's Theorem is an
> alternate way to calculate it. If you write a program that uses the
> distance form c = sqrt(a^2 + b^2) you will suffer from the lose of ha
On Monday, May 25, 2015 at 1:27:43 PM UTC-7, Gary Herron wrote:
> This is a statement about floating point numeric calculations on a
> computer,. As such, it does apply to Python which uses the underlying
> hardware for floating point calculations.
>
> Validity is another matter. Where did yo
On Monday, May 25, 2015 at 1:27:24 PM UTC-7, Christian Gollwitzer wrote:
> Wrong. Just use the built-in function Math.hypot() - it should handle
> these cases and also overflow, infinity etc. in the best possible way.
>
> Apfelkiste:~ chris$ python
> Python 2.7.2 (default, Oct 11 2012, 20:14:37)
Am 25.05.15 um 21:21 schrieb ravas:
I read an interesting comment:
"""
The coolest thing I've ever discovered about Pythagorean's Theorem is an
alternate way to calculate it. If you write a program that uses the distance
form c = sqrt(a^2 + b^2) you will suffer from the lose of half of your
av
On 05/25/2015 12:21 PM, ravas wrote:
I read an interesting comment:
"""
The coolest thing I've ever discovered about Pythagorean's Theorem is an
alternate way to calculate it. If you write a program that uses the distance
form c = sqrt(a^2 + b^2) you will suffer from the lose of half of your
a
El 25/05/15 15:21, ravas escribió:
I read an interesting comment:
"""
The coolest thing I've ever discovered about Pythagorean's Theorem is an
alternate way to calculate it. If you write a program that uses the distance
form c = sqrt(a^2 + b^2) you will suffer from the lose of half of your
ava
On 05/08/2010 10:33 PM, 3Jane wrote:
You could interpret [[1,2,3,4],[5,6,7,8]] as a tree and
your task as traversal of its leaves. All solutions before
would not work with trees with bigger height.
Here is how to traverse such trees recursively:
def eventualPrint(x):
for v in x:
i
Dennis Lee Bieber wrote:
On Sat, 27 Feb 2010 13:00:32 +1300, Gib Bogle
declaimed the following in
gmane.comp.python.general:
The PyQt4 problem results from having copies of the Qt DLLs in directories that
are in the PATH, as Doug Bell discovered. In my case I have two programs that
use Qt, A
The PyQt4 problem results from having copies of the Qt DLLs in directories that
are in the PATH, as Doug Bell discovered. In my case I have two programs that
use Qt, AMD CodeAnalyst and Matlab. If I rename BOTH these directories I can
import the PyQt4 modules.
Since this behaviour did not oc
The PyQt4 problem results from having copies of the Qt DLLs in directories that
are in the PATH, as Doug Bell discovered. In my case I have two programs that
use Qt, AMD CodeAnalyst and Matlab. If I rename BOTH these directories I can
import the PyQt4 modules.
Since this behaviour did not oc
The point of my question was that sys.path is clearly not being used in this
case. When I start Python sys.path includes D:\python26\lib\site-packages which
seems to be the Python default. Using sys.path.append I have tried adding both
D:\python26\lib\site-packages\PyQt4 and D:\python26\lib\si
Chris Rebert wrote:
On Fri, Feb 26, 2010 at 12:45 PM, Gib Bogle
wrote:
How can I interrogate Python to find out where it is looking to find the
PyQt4 DLLs in a Windows installation?
import sys
print(sys.path)
Note this thread:
http://www.mail-archive.com/p...@riverbankcomputing.com/msg20121
On Fri, Feb 26, 2010 at 12:45 PM, Gib Bogle
wrote:
> How can I interrogate Python to find out where it is looking to find the
> PyQt4 DLLs in a Windows installation?
import sys
print(sys.path)
Cheers,
Chris
--
http://blog.rebertia.com
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Hi Mr.Posner & nn,
Thank your for your time & effort. I never knew that for...ever
combination even existed. I would keep these insights in mind in the
future.
Thanks again,
Prasad
On Feb 25, 10:57 pm, John Posner wrote:
> On 2/25/2010 7:23 AM, prasad_chand wrote:
>
>
>
> > Hi,
>
> > I use pyth
prasad_chand wrote:
> Hi,
>
> I use python to do simple math problems as a hobby.
>
> I have made a program that finds the number of divisors(factors) of a
> given number. I am hoping to improve my language skills, specifically
> I would like to re-write the function "prime_factors" more graceful
Robert Kern wrote:
On 2009-11-23 11:49 AM, W. eWatson wrote:
I'm looking the 300+ page pdf of the Guide to Numpy. Is there a more
concise and practical guide to its use in science and mathematics?
You will want to ask numpy questions on the numpy mailing list:
http://www.scipy.org/Mailing_L
On 2009-11-23 11:49 AM, W. eWatson wrote:
I'm looking the 300+ page pdf of the Guide to Numpy. Is there a more
concise and practical guide to its use in science and mathematics?
You will want to ask numpy questions on the numpy mailing list:
http://www.scipy.org/Mailing_Lists
You may also f
On Dec 6, 12:19 am, Steven D'Aprano <[EMAIL PROTECTED]
cybersource.com.au> wrote:
> On Fri, 05 Dec 2008 07:44:21 -0800, eric wrote:
> > I like to believe that the less the 'debug pointer' stands in the python
> > code, the fastest the code is (or is potentially)
>
> What's a debug pointer?
>
> Pre-
On Fri, 05 Dec 2008 07:44:21 -0800, eric wrote:
> I like to believe that the less the 'debug pointer' stands in the python
> code, the fastest the code is (or is potentially)
What's a debug pointer?
Pre-mature optimization is the root of evil in programming. Unless you
have actually *measured*
On Dec 5, 3:44 pm, "Mark Tolonen" <[EMAIL PROTECTED]> wrote:
> "eric" <[EMAIL PROTECTED]> wrote in message
>
> news:[EMAIL PROTECTED]
>
> > def flag(IGNORECASE=False, LOCALE=False, MULTILINE=False,
> > DOTALL=False, UNICODE=False, VERBOSE=False):
> > vals = [IGNORECASE, LOCALE, MULTILINE, DOTALL
eric wrote:
Hi,
I've got this two pieces of code that works together, and fine
def testit():
for vals in [[i&mask==mask for mask in [1<', flag(*vals)
def flag(IGNORECASE=False, LOCALE=False, MULTILINE=False,
DOTALL=False, UNICODE=False, VERBOSE=False):
vals = [IGNORECASE, LOCALE, MULT
"eric" <[EMAIL PROTECTED]> wrote in message
news:[EMAIL PROTECTED]
def flag(IGNORECASE=False, LOCALE=False, MULTILINE=False,
DOTALL=False, UNICODE=False, VERBOSE=False):
vals = [IGNORECASE, LOCALE, MULTILINE, DOTALL, UNICODE, VERBOSE]
filtered = map( lambda m:m[1],filter( lambda m: m[0]
>
> Google doesn't seem to let you add attachments so I've put a sample of
> the output here:http://www.qtrac.eu/libindex.html
> at the bottom of the page there is a link to the ~100 line libindex.py
> script that generated it.
I like it. thanks.
--
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> > [1, 2, 2, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 5, 6, 6, 6, 6, 6, 6, 7, 7,
> > 7, 7, 7, 7, 7, 8, 8, 8, 8, 8, 8, 8, 8]
> [i+1 for i in range(8) for j in range(i+1)]
[i for i in range(9) for j in range(i)]
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Levi Self wrote:
> This probably seems very trivial, maybe even a bit silly, but I was
> wondering if someone has a better list comprehension that does the
> same thing as this one:
>
> >>> print [[[i]*i for i in range(1,9)][j][k] for j in range(8) for k
> in range(j+1)]
> [1, 2, 2, 3, 3, 3, 4, 4,
[EMAIL PROTECTED] wrote:
> Does it really need to be a regular expression? Why not just write a
> short function that breaks apart the input and validates each part?
>
> def IsEmail(addr):
> 'Returns True if addr appears to be a valid email address'
>
> # we don't allow stuff like [EMAIL PROT
[EMAIL PROTECTED] wrote:
> rbt> re.compile('([EMAIL PROTECTED])')
> rbt> re.compile(r'[EMAIL PROTECTED],4}')
> rbt> re.compile('(\S+)@(\S+)')
>
> rbt> All of these will find email addys, but they also find other
> rbt> things.
>
> I think the only way to decide if your regular
[EMAIL PROTECTED] wrote:
> Does it really need to be a regular expression? Why not just write a
> short function that breaks apart the input and validates each part?
>
> def IsEmail(addr):
> 'Returns True if addr appears to be a valid email address'
>
> # we don't allow stuff like [EMAIL PROT
Does it really need to be a regular expression? Why not just write a
short function that breaks apart the input and validates each part?
def IsEmail(addr):
'Returns True if addr appears to be a valid email address'
# we don't allow stuff like [EMAIL PROTECTED]@biff.com
if addr.count('@') !=
Jim wrote:
> There is a precise one in a Perl module, I believe.
> http://www.ex-parrot.com/~pdw/Mail-RFC822-Address.html
> Can you swipe that?
>
> Jim
>
I can swipe it... but it causes my head to explode. I get unbalanced
paratheses errors when trying to make it work as a python re... it mak
* rbt wrote:
> Is it possible to write an re that _only_ matches email addresses?
No. The only way to check if the matched thing is a mail address is to send
a mail and ask the supposed receiver whether he got it.
The grammar in RFC 2822 nearly matches anything with an @ in it. So, how
accurate
Jim> http://www.ex-parrot.com/~pdw/Mail-RFC822-Address.html
Maybe Cafe Express could be convinced to put that on a t-shirt...
Skip
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rbt> re.compile('([EMAIL PROTECTED])')
rbt> re.compile(r'[EMAIL PROTECTED],4}')
rbt> re.compile('(\S+)@(\S+)')
rbt> All of these will find email addys, but they also find other
rbt> things.
I think the only way to decide if your regular expression does what you want
is to pro
OMG, that is so ugly :D
Jim wrote:
> There is a precise one in a Perl module, I believe.
> http://www.ex-parrot.com/~pdw/Mail-RFC822-Address.html
> Can you swipe that?
>
> Jim
>
>
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There is a precise one in a Perl module, I believe.
http://www.ex-parrot.com/~pdw/Mail-RFC822-Address.html
Can you swipe that?
Jim
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