Debian (development tips)

Posted on Saturday, Dec 13, 2014 in programming • Tagged with debian, help, documentation, libraries, pil, libjpeg, locale, matplotlib, libxml, ubuntu, freetype, postgresql, database, scipy

These are some extra steps that I've found necessary when starting development in a recently-installed Debian machine.

Jpeg support in PIL and pillow.

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$ sudo apt-get install libjpeg libjpeg-dev libfreetype6 libfreetype6-dev zlib1g-dev
$ sudo ln -s /usr/lib/`uname -i`-linux-gnu/libfreetype.so /usr/lib/
$ sudo ln -s /usr/lib/`uname -i`-linux-gnu/libjpeg.so /usr/lib/
$ sudo ln -s /usr/lib/`uname -i`-linux-gnu/libz.so /usr/lib/

Installing lxml in Python (Debian based).

If you're getting the "fatal error: libxml/xmlversion.h: No such file or directory" error, just install the following development files:

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$ sudo apt-get install python-dev libxml2-dev libxslt1-dev

Problems with 'matplotlib' and freetype.

If you're having problems installing matplotlib in a Python virtualenv, and are getting the 'freetype missing' error, you sould install the development files for freetype, and (in most cases) rebuild the python dependencies for matplotlib.

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$ sudo apt-get  -u install libfreetype6-dev
$ sudo apt-get build-dep python-matplotlib

After that, you can just use pip normally to install matplotlib

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$ pip install matplotlib

PS. I know of cases where you have to update python-virtualenv and python-pip after you use build-dep. Just apt-get upgrade your installation. Today I learned about the 'pydoc' command from Python.

Problems with locale

In some machines I've found problems when setting locales from Python. First check the results of running

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$ locale

In my case is:

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LANG=es_VE.UTF-8
LANGUAGE=es_VE:es
LC_CTYPE="es_VE.UTF-8"
LC_NUMERIC="es_VE.UTF-8"
LC_TIME="es_VE.UTF-8"
LC_COLLATE="es_VE.UTF-8"
LC_MONETARY="es_VE.UTF-8"
LC_MESSAGES="es_VE.UTF-8"
LC_PAPER="es_VE.UTF-8"
LC_NAME="es_VE.UTF-8"
LC_ADDRESS="es_VE.UTF-8"
LC_TELEPHONE="es_VE.UTF-8"
LC_MEASUREMENT="es_VE.UTF-8"
LC_IDENTIFICATION="es_VE.UTF-8"
LC_ALL=

Then use:

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import locale

try:
    locale.setlocale(locale …

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(Local) Online Python Documentation

Posted on Friday, Oct 15, 2010 in programming • Tagged with python, help, documentation

Today I learned about the pydoc command from Python. Even if you're offline you can access the standard library documentation running from a local copy using the command mentioned above.

Simply introduce this command in your terminal:

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$ pydoc -p 8000

Then you can go to http://locahost:8000. This way you can browse the documentation for all your installed Python modules in the same way you'd use the 'help' command from the Python CLI.

[1] http://docs.python.org/library/pydoc.html

[2] http://pydoc.org/