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  1. Doing calculations with Python

    As an engineer I do a lot of calculations. These can be done with pen and paper and a calculator, in an IPython notebook or in a throwaway spreadsheet. All of these methods have shortcomings, though.

    Pen and paper is hard to share and (in my case) hard for others to read. In IPython you can assign the results of calculations to a variable, but you have to perform a separate action to display them. And spreadsheets in general show you the results but not the calculations.

    So I wrote a simple function in Python to help me with that. Using this function I can print both simple assignments and relatively complex calculations. And it shows both the calculation and the result.

  2. Structures in Python

    Sometimes I miss the C’s plain old struct in Python.

    Of course Python has dictionaries, but I prefer to write a.b over a['b'].

    Here are several ways of doing something akin to a struct in Python.

  3. Building gphoto2-ffi on FreeBSD

    Download

    Clone the repository from https://github.com/jbaiter/gphoto2-cffi.

    > cd ~/github
    > git clone https://github.com/jbaiter/gphoto2-cffi
    

    Build

    I had to specify where to find the include files.

    > env C_INCLUDE_PATH=/usr/local/include python3 setup.py build
    

    Install and clean-up

    # python3 setup.py install
    # python3 setup.py clean …
  4. Removing big files from git history

    By accident I checked 60-odd full-size photographs into the git history of my website. I shrunk them in a next commit, but the history was still there leading to a bloated .git directory. This took a lot of time when making backups. This documents how I cleaned up this mess.

  5. Using gnuplot from Python

    According to my revision control systems (rcs in those days), I’ve been using gnuplot to make graphs since at least 2002. And I’ve got it set up via a custom gnuplotrc to match the style of the TeX documents I often use the graphs in.

    At work we have an Instron 3369 machine for material testing. Recently, I wanted to visualize some tensile test data in ways that I couldn’t get into the test report.


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