Cleaning up Python – and old libraries

Newer Ubuntu releases do not even pre install Python2, and after an upgrade and installing latest Python3.x included in the release, you likely have some old ones there too. Since you most likely will not be using the python2 unless you use some very old library, you can clean them up, clear a lot of disk space and use the “python3” / “pip3” command instead.

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Injecting commands and debugging a running Python program, with Project Euler example

How often has it happened to you… you build a simple script to calculate something, run some bulk process, and coming back after an hour or so it just hangs with no output. Is it doing something or stuck? You could debug it, using WinPdb or Visual Studio Code debugger or GDB to run it step by step, but that would lose the time that it has been processing. Instead, you can use Pyrasite, a program for looking in to a running Python script!

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Linux 5.9

Recently, Linux 5.9 was released! While folks are unlikely to see this in any distribution very soon, it brings some improvements that will be a clear reason that we will hear about it very soon (ok, enough ham radio jokes 🙂 )

Although it’s not something particularly recommended for your main system, but you could install it now – in fact with kernels of Linux you can generally switch it out and if it doesn’t work, just select the old one at the boot screen.

Human pose estimation with Python and Gluoncv

Human pose estimation is something useful for robotics/programming as you can see what position a person is in a picture. For last weekend’s Hackrithmitic I did an experiment for fun using computer vision pose estimation. To start with I found several possibilities with available libraries:

  • Tensorflow js has been used to say, don’t touch your face, but it takes a massive amount of cpu.
  • Openpose is a popular one, only licensed for noncommercial research use, and there is a Opencv example for it that doesn’t quite show how to use it.
  • AlphaPose is supposedly faster and has a more clear license and possibility for commercial use – if you want that as a possibility. I checked out the install instructions and worked but for “python3” instead of “python”. It also misses obvious step of installing cuda for your Nvidia system before running.
  • GluonCV is another, which seems more user friendly. This one I was able to get running in a few minutes with their example:
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Fixing Ubuntu Python-Pip

After you’ve upgraded your Ubuntu machine a few times, you might find that free disk space is low and some Python commands have issues. Programs like Bleachbit can help you clear old packages or cache that you don’t need, but sometimes you need a minor manual fix as documented here. As you may know, Pip is the main package management you’ll use to install packages you use, so this can be problematic.

After upgrading 16.04 to 18.04, I got an error on command line “pip”:

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