Author Archives: Thomas Cokelaer

nosetests: setup and teardown methods

Posted on June 20, 2012 by Thomas Cokelaer

nosetests is a tool used to build unit tests in python. Here below, I show an example on how to write a class that will perform some tests (test that a directory that has been created exists indeed). One issue … Continue reading →

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graphviz plot without graphviz…

Posted on April 10, 2012 by Thomas Cokelaer

Graphviz is a standard tools that is used to create images of graphs (see http://www.graphviz.org/). The graph are described thanks to a language. For instance the graph represented in the following image would be represented as A -> B B … Continue reading →

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How to plot left and right axis with matplotlib

Posted on April 3, 2012 by Thomas Cokelaer

Sometimes, it is convenient to plot 2 data sets that have not the same range within the same plots. One will use the left y-axes and the other will use the right y-axis. With matplotlib, you need to create subplots … Continue reading →

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How to call R plotting function from python using rpy2

Posted on April 3, 2012 by Thomas Cokelaer

Python has already very good librairies from plotting (e.g., matplotlib, mayavi), however, it is sometimes useful to use some of the plotting functionalities offered by R. Thanks to the rp2 package, it is quite easy. Let us try to use … Continue reading →

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ipython

Posted on March 23, 2012 by Thomas Cokelaer

If you start to use python, just install ipython to ease your life by having a more interactive python shell. http://ipython.org/ A nice feature in the ability to embed matplotlib plot. Start with this option: ipython qtconsole -pylab inlineipython qtconsole … Continue reading →

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linux: How do I know the number of memory cards

Posted on March 22, 2012 by Thomas Cokelaer

The dmidecode command dumps lots of information about your system. The option memory gives you details about your memory card. In particular how many are installed (e.g., 2x2Gb or 1x 4Gb) sudo dmidecode -t memorysudo dmidecode -t memory

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VIM: switch all text to lower case

Posted on March 22, 2012 by Thomas Cokelaer

You can change the case of a character by typing ~ , however, if you want to change all text to the same case (let us say lower case here), then you should enter the visual mode. Go to the … Continue reading →

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How to embedded data files in python using setuptools

Posted on March 2, 2012 by Thomas Cokelaer

Within a Python package, it is useful to provide data files. These files are not python modules so you do not want to place same together with your module. Let us put them in a directory share/data. Suppose you have … Continue reading →

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HTML: How to redirect to another page

Posted on February 3, 2012 by Thomas Cokelaer

  <meta HTTP-EQUIV="REFRESH" content="0; url=http://whatever"> <meta HTTP-EQUIV="REFRESH" content="0; url=http://whatever"> Note the syntax where content=”0; is not a typo. The content field contains both the URL to be redirect to and the delay (in seconds). In general, you may want to … Continue reading →

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installing rpy2 with different R version already installed

Posted on January 31, 2012 by Thomas Cokelaer

The easiest way to install a python package is to use easy_install (or pip), so to install rpy2, type: easy_install rpy2 To test that it is properly installed, type: import rpy2; from rpy2 import robjects; robjects.r(“version”) If this code works, … Continue reading →

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