Re: Writing binary files in windows
On 02/12/2011 05:20 AM, Abhishek Gulyani wrote:
When I write binary files in windows:
file = open(r'D:\Data.bin','wb')
file.write('Random text')
file.close()
and then open the file it just shows up as normal text. There is
nothing binary about it. Why is that?
Sorry if this is too much of a noobie question. I tried googling
around but couldn't find an answer.
But then, you opened the file you created in Notepad and saw that the
lines weren't wrapping maybe?
It all comes down to Line endings. Read here to see what LF vs. CRLF is
all about http://en.wikipedia.org/wiki/Newline#Representations
You see, when you read a file, Python converts both LF and CRLF to "\n".
When you write a "\n" to a file Python writes CRLF in Windows and just
LF in Unix machines.
That'd be a heck troublesome when dealing with binary files, hence the
'b' flag. It basically means *Don't convert newlines", and it's pretty
common in software.
So, to answer your question: If you're only writing text to a file,
you'll only see a difference if your external text editor isn't smart
enough to treat both LF and CRLF as newlines. Like Notepad did back in
the day, and maybe still does.
But if you're writing binary stuff, it makes all the difference in the
world.
Nick
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Re: 'reload M' doesn't update 'from M inport *'
I know I have more radical options, such as starting a new IDLE window. That would save me time, but I'd like to take the opportunity to understand what is happening. Surely someone out there knows. Frederic Or you can restart the IDLE shell with CTRL+F6. If you can't restart it, you're probably not using an IDLE subprocess: On linux, make sure the menu item doesn't use "-n" in the command On Windows, first open IDLE, then open the file, or change the Open command to not use the "-n" flag. Sorry to not chip in to your question, frankly, Steven nailed it! Just thought to share an IDLE tip :) Nick -- http://mail.python.org/mailman/listinfo/python-list
Re: Hello
Hello Dani! IDLE is very friendly for new users and has got me a long way when I was starting. You also can't beat that it comes bundled with Python. I'd also like to suggest the Python-Tutor list http://mail.python.org/mailman/listinfo/tutor for your "new-user" questions. Lots of helpful folk there, myself included. Nick On 07/09/2010 07:31 PM, Dani Valverde wrote: Hello! I am new to python and pretty new to programming (I have some expertise wit R statistical programming language). I am just starting, so my questions may be a little bit stupid. Can anyone suggest a good editor for python? Cheers! Dani -- http://mail.python.org/mailman/listinfo/python-list
Re: iptcinfo: Can not import: Newbie not really knowing what he is doing
Hi Richard! I have downloaded iptcinfo and placed it in python27\Lib\site-packages \iptcinfo I guessed that was the right place, because that is where PIL ended up, but that had a fancy installer with it. You did place it in the right path, but the "fancy installer" does one more thing, it registers the package into the python-path, so python can get to it. I've long switched from windows unfortunately and can't remember the way it does this though, so you can do it manually. Have some good news though: I looked in the IPTCinfo package and it does indeed include a setup.py, which is a standard way of installing python packages. All you need to do is unpack the package to any folder and run setup.py install from that folder, which should take care of everything for you. Some documentation on installing packages for you to read: http://docs.python.org/install/ Nick -- http://mail.python.org/mailman/listinfo/python-list
Re: Nice way to cast a homogeneous tuple
On 07/28/2010 04:15 PM, wheres pythonmonks wrote:
f( *map(lambda x: int(x), struct.unpack('2s2s2s','123456')))
102
But this seems too complicated.
Well, you don't need the lambda at all
int ===lambda x: int(x)
So just write
It's like writing:
def myint(x):
return int(x)
Nick,
Warm thanks to Steven D' Aprano who taught me that just yesterday in the
Tutor list ;)
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Re: Nice way to cast a homogeneous tuple
Ep, that missing line should be:
On 07/28/2010 04:27 PM, Nick Raptis wrote:
On 07/28/2010 04:15 PM, wheres pythonmonks wrote:
f( *map(lambda x: int(x), struct.unpack('2s2s2s','123456')))
102
But this seems too complicated.
Well, you don't need the lambda at all
int ===lambda x: int(x)
So just write
f( *map(int, struct.unpack('2s2s2s', '123456')))
Pretty compact now, isn't it?
It's like writing:
def myint(x):
return int(x)
Nick,
Warm thanks to Steven D' Aprano who taught me that just yesterday in
the Tutor list ;)
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Re: default behavior
On 07/29/2010 09:12 PM, wheres pythonmonks wrote: How do I build an "int1" type that has a default value of 1? You mean something like: >>> x = int() >>> x 0 >>> def myint(value=1): ... return int(value) ... >>> myint() 1 >>> That's ugly on so many levels.. Anyway, basic types (and almost everything else) in Python are classes. You can always subclass them to do whatever you like [Hopefully no speed penalty.] I am thinking about applications with collections.defaultdict. What if I want to make a defaultdict of defaultdicts of lists? [I guess my Perl background is showing -- I miss auto-vivification.] Ah, python is no perl. Then again, perl is no python either. - Random pseudo-Confucius quote Have fun, Nick -- http://mail.python.org/mailman/listinfo/python-list
