Dryice Liu's Blog » python

Copy file in the order of their name

dryice — Wed, 30 Jan 2008 10:11:57 +0000

Last weekend I got myself a small MP3 player called Q12.

I really like this small one cause I can carry it everywhere and save me some time while I’m walking or waiting.

It support file/folder visiting of the files, and not support MP3 tag and organized with artiste, album, etc like Apple IPod. This is the reason I prefer it over the Sandisk Clip. Because most of the time I’ll use it to listen podcasts or audio books.

However there is a problem: It won’t sort the files. I just can’t find any options to sort the files in the menu system or the user user manual. Then I thought it might sort the files by their access time, or create time, so I wrote mp3 reorg , which will change the atime/ctime of all the files so the fils should appear earlier will get an earlier atime/ctime. However it turns out this little mp3 don’t obey that too, they just read the FAT table and don’t do any sort! Finially I have to wrote another one, mp3 copy, to copy the files in the order I want.

Just put them here in case anyone could find them useful. Note “create time” is a dos/windows only thing, we don’t have this on (most) Unix systems. If your mp3 use atime (access time) or ctime (changed time), you could use the “mp3reorg” script on Unix platform too, just comment out the lines with “win32″ in it. The “mp3 copy” script works cross platform, though.

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pylons

dryice — Wed, 18 Apr 2007 14:36:00 +0000

I gave Pylons a try today, followed the turorials, read some
documents, and compared it with my current Python web frame work of
choice: TurboGears.

Though many people say good words for pylons, I believe TurboGears is
still a good choice for me at this time:

TG is one year older than Pylons, which means more stable most of
the time
TG comes with more tools that is handy. Say for
internationalization, TG is much easier. It can handle strings in
both the Python files and template. It also do the language choose
automatically.
The major difference between the two is the dispatching
mechanisms. Though Pylons’ URL matching is more flexable, I found
the TurboGears tree like structure quite nature, as some one from
Quixote.
TurboGears comes with AJAX support
TurboGears comes with a good widget library, and many more in the
cogbin. ToscoWidgets, which is seperated from TurboGears, will be
used in the future release of both. And for sure it will be much
easier to switch to ToscoWidgets from TG than from Pylons.
One thing TG lakes is the caching. However when it comes in a
future release, I can benefit from it with little or no change of
my application code.
TG returns a dict/JSON from the controller. This seperates the view
and controller, and makes multiple views (say HTML and RSS feed)
quite easier. While the “c” global accross controller and templage
is, well, rather urgly from my point of view.

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Dynamic handling of ‘virtual file names’, or URL paths with file extensions

dryice — Fri, 13 Apr 2007 10:39:00 +0000

Well TurboGears uses CherryPY as the URL dispatcher. And by default
it uses the object structure as a tree like structure for the URL
paths, like the file system structure.

This works fine most of the time. However, the Python function name is
quite restrict than what we can use in an URL. For example, the “.”
character is not allowed. So, for example, if I want to make the URL
looks the old traditional way, like “/index.html”. I’ll need to write
a BIG elif clause in the default() function.

The good news is that after some digg on Google I found
This CherryPY ticket. And the solution is simple: I could use
index_html as the function name, and when user types index.html in the
URL, CherryPY will find index_html

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Bicyclerepair man: a refactoring code browser

dryice — Mon, 05 Mar 2007 07:10:00 +0000

On my way of finding a tool to easy find defination/reference of Python code, I found Bicyclerepair man. First I just use it to find definatins and references. And after some hacking, it works pretty good with my Emacs.

After reading some document, I find it opens a BIG door: it’s a tool to help me refactoring my code. That is, make my codes more structure, smaller, and easy to read.

Some features are, make part of a function to be a seperate function, part of an expression to be a seperate expression, move classes among modules.

I haven’t use these features but I’ve already love it

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quixote is not ready for python 2.5

dryice — Wed, 11 Oct 2006 07:04:00 +0000

I tried to upgrade to Python 2.5 today, however, some of the packages I use daily is not ready, including quixote.

At least on change in compile.ast.From makes quixote 2.4 not working in Python 2.5.

I think I’ll stick with Python 2.4 till more packages come to work with 2.5.

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challenge 6, continued

dryice — Mon, 08 May 2006 06:51:00 +0000

A year has passed since I visited Python Challenge the last time. And it’s not easy to start it again I’ve got a project that deals with Python image process, so I spend some time on the PIL handbook. And after that, I think trying this challenge is a good practice

However after I load the image

import Image

im = Image.open("channel.jpg")

I don’t know what to do next. I tried to exam the various attributes of the image, but got nothing.

Think it again on “It really looks like a Y, isn’t it? now, go back. ” at http://www.pythonchallenge.com/pc/def/y.html. What if the zip goes back? Hmmm, it should looks like a “1″ or “l”. then I tried http://www.pythonchallenge.com/pc/def/l.html because “1.html” has already been taken. OK, something there! “yes. but there are more. ” Good! I tried 2, 3, 6, 33 “l”s and several combination with “w”, “o”, and “0″, but all 404.

I think now the problem is to find out how many “l”s are there. I tried every attributes of ImageStat but they are all tooooo big. No more hint. I think I should wait the next time.

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Captcha

dryice — Mon, 17 Apr 2006 02:46:00 +0000

Captcha stands for “completely automated public Turing test to tell computers and humans apart”, which is the small images we usually see when registering or logining to some systems like free email. It is developted to protect from robots. See the wikipidia page for detail.

There are several Python packages implementing this:

I haven’t look them into detail but looks they are not strong enough if someone like pwntcha want to decode it. Captcha is not a good idea according to W3C. They are working on a draft and this presentation explains why it’s a bad idea and provides some alternatives. Though I don’t think most of the alternatives are practive at this time.

Till now all the comments to my blog are from spammers, though not a big amount yet. I think I’ll imply a captcha check if it get worse.

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compare strings disregarding whitespace without RE

dryice — Tue, 21 Mar 2006 02:53:00 +0000

There is an interesting topic in the python.list about comparing two strings deiregarding whitespace without re. As the discussion went on, there cames two different requirements:

normalize whitespace That is, “a\n b c” == “a b \n c” but “ab c” <> “a bc”
totally ignore withespace Both “a\n b c” == “a b \n c” and “ab c” == “a bc”

The first solution looks like this

import string

NULL = string.maketrans("","")

WHITE = string.whitespace

def compare(a,b):
“”"Compare two strings, disregarding whitespace -> bool”"”
return a.translate(NULL, WHITE) == b.translate(NULL, WHITE)
This one first make a do-nothing translateion table and utilize string.translate to delete all the whitespaces. So this meets requirement (2).

However this won’t work with unicode string. This is because the plain text translate take 2 arguments and the first one is a 256 char long “translation table” returned by string.maketrans but the unicode translate takes only 1 argument and it is a dict.

Here is how the unicode translate works:

>>> u’banana’.translate({ord(’a'):u’ay’})

u’baynaynay’

or use it for delete:

>>> u’banana’.translate({ord(’a'):None})

u’bnn’

So for requirement (2), it looks like

nowhite = dict.fromkeys(ord(c) for c in string.whitespace)

def compare(a,b):
“”"Compare two strings, disregarding whitespace -> bool”"”
return a.translate(nowhite) == b.translate(nowhite)
It’s annoying to have these two solution for plain text and unicode. This might be why translate is marked “obsolete” in the Python documents.

So someone made a wrapper with the isinstance check:

import string

NULL = string.maketrans("","")

WHITE = string.whitespace

NO_WHITE_MAP = dict.fromkeys(ord(c) for c in WHITE)

def compare(a,b):

"""Compare two basestrings, disregarding whitespace -> bool"""

if isinstance(a, unicode):

astrip = a.translate(NO_WHITE_MAP)

else:

astrip = a.translate(NULL, WHITE)

if isinstance(b, unicode):

bstrip = b.translate(NO_WHITE_MAP)

else:

bstrip = b.translate(NULL, WHITE)

return astrip == bstrip

And for requirement (1), there is a much clever and easier way:

def compare(a,b):

return a.split() == b.splite()

This is because split() does all the normalize thing and splite the string with whitespace. Also this works with Unicode too.

Sure the Unicode translate can work for this requirement:

nowhite = dict.fromkeys(ord(c) for c in string.whitespace, " ")

def compare(a,b):
“”"Compare two strings, disregarding whitespace -> bool”"”
return a.translate(nowhite) == b.translate(nowhite)
The only change is how the dict is formed: by default dict.fromkeys will use None as the value so the whitespace is deleted, but we could replace them with a single ” ” so it is normalized.

And finially, the RE way, of cause works with Unicode:

totally ignore::

import re

def compare(a, b):

"""Compare two basestrings, disregarding whitespace -> bool"""

return re.sub("\s*", "", a) == re.sub("\s*", "", b)

normalize::

def compare(a, b):

"""Compare two basestrings, normalizing whitespace -> bool"""

return re.sub("\s*", " ", a) == re.sub("\s*", " ", b)

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playsh: MUD like programming environment for pythoner

dryice — Tue, 21 Mar 2006 01:38:00 +0000

There is an article on wired news about a new game, playsh. It is like a MUD but you can do python programming in it. Looks a good way to learn Python programming.

I didn’t play too much with MUD in the old 1990s days but this looks interesting. However there are two requirements for the package not in the FreeBSD ports tree: html2text and simplejson. So I haven’t try it out.

Reference: (from the author’s blog)

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unicode(str, "utf-8") and str.encode("utf-8")

dryice — Wed, 08 Mar 2006 16:00:00 +0000

the key is, unicode in Python is an object, unicode(str, “utf-8″) makes that object from an utf-9 str, and str.encode(”utf-8″) encode a string to the utf-8 encoding.

To write unicode-aware python code, I’ll need to:

when getting data, use unicode(str, “the_encoding”) to get an unicode object
use unicode object inside my program, like all internal strings should be u”some_thing”
when output, convert the unicode object to whatever fits, that is, use str.encode(”the_encoding”)

Good reference:

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