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How to change the version of Python catkin uses

asked 2016-01-08 12:49:08 -0500

Albatross gravatar image

I'm trying to create a package with catkin_create_pkg but it is failing with this error:

Traceback (most recent call last):
File "/usr/local/bin/catkin_create_pkg", line 10, in <module> from catkin_pkg.package_templates import create_package_files, PackageTemplate ImportError: No module named 'catkin_pkg'

I think this is because it is trying to use Python 3 rather than Python 2. (running python -c "import catkin_pkg" works, but running python3 -c "import catkin_pkg" gives the import error)

Is there a nice way to switch it to always use Python 2 instead (the default Python on my system, and the one I prefer to use)? I just installed it with apt-get following the tutorials. Other stuff like catkin_make and catkin_init_workspace work fine, catkin_create_pkg was the first command I ran into that didn't work.

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Which versions of Linux and ROS are you using? The version of catkin_create_pkg that you're calling is in /usr/local; how did you install it?

ahendrix gravatar image ahendrix  ( 2016-01-08 13:10:27 -0500 )edit

I'm using Ubuntu 14.04 with ROS Indigo. I think installed it with apt-get install python-catkin-pkg, I also did an install of ros-indigo-desktop-full earlier when going through the tutorials, which may have included it?

Albatross gravatar image Albatross  ( 2016-01-08 13:54:36 -0500 )edit

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answered 2016-01-08 17:07:51 -0500

ahendrix gravatar image

I've confirmed that catkin_create_pkg is included as part of the catkin_pkg python package (which you can install on Ubuntu through the python-catkin-pkg apt package). This means that if you have python-catkin-pkg installed, you should have catkin_create_pkg in /usr/bin

Since your version of catkin_create_pkg appears to be located in /usr/local/bin, I suspect you ALSO installed catkin_pkg though pip (or pip3) at some point. You should attempt to uninstall the version of catkin_pkg that was installed through pip:

pip uninstall catkin_pkg

(if you installed as root, you may need to run the unistall with sudo).

Note that this will not remove the version of catkin_pkg that was installed through apt (which is good)

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Thanks! I've got it working now. Uninstalling with pip or pip3 didn't fix it (got a message saying it couldn't find anything to uninstall) so what I ended up doing was just renaming the file in /usr/local/bin to something else so it wouldn't use that one.

Albatross gravatar image Albatross  ( 2016-01-11 11:06:47 -0500 )edit

I checked the date on catkin_create_pkg from /usr/local, turns out it was created in 2013, so it must have been from when I was mucking around with ROS in the past. I thought I uninstalled all of the old stuff and replaced it with the new version, but it seems a few things were missed.

Albatross gravatar image Albatross  ( 2016-01-11 11:14:51 -0500 )edit

If you have old files installed by pip in /usr/local, and you're certain you don't need them any more, it's safe to delete them. (That's probably the case here). You may want to look through /usr/local/bin and /usr/local/lib/python2.7/dist-packages for any other old ROS packages and remove them too.

ahendrix gravatar image ahendrix  ( 2016-01-11 12:13:42 -0500 )edit

answered 2019-04-28 13:17:58 -0500

Fisherman gravatar image

If you use Anaconda3 for Python you have a PATH to python3 interpreter in your .bashrc file. You can change it to python2 (/usr/bin..) for example and your problem will solved.

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Asked: 2016-01-08 12:49:08 -0500

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Last updated: Jan 08 '16