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Using fuerte with python 3

asked 2012-04-24 22:02:22 -0500

languitar gravatar image

updated 2014-01-28 17:12:05 -0500

ngrennan gravatar image

I have seen that several issues regarding python 3 support have been solved recently, e.g. [1]. However, I could not find any information how to actually use the new release with python 3? That means how do I get the python libraries compiled and installed in a python3-compatible pythonpath etc.?

[1] https://code.ros.org/trac/ros/ticket/3166

Ok, trying michikarg's suggestion I end up in this error:

>>> import roslib
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/vol/corcse/ros-fuerte/x86_64/src/ros-underlay/ros/core/roslib/src/roslib/__init__.py", line 50, in <module>
    from roslib.launcher import load_manifest
  File "/vol/corcse/ros-fuerte/x86_64/src/ros-underlay/ros/core/roslib/src/roslib/launcher.py", line 42, in <module>
    import rospkg
ImportError: No module named rospkg

jwienke@augit:/vol/corcse/ros-fuerte/x86_64/src/PyYAML-3.10$ echo $PYTHONPATH
/vol/corcse/ros-fuerte/x86_64/lib/python3.1/site-packages:/vol/corcse/ros-fuerte/x86_64/src/ros-underlay/ros/core/roslib/src/

With the patch mentioned below I am now able to use roslib. However rospy and std_msgs do not work:

jwienke@augit:/vol/corcse/ros-fuerte/x86_64/src/ros-underlay/ros/core/roslib/src/roslib$ python3
Python 3.1.2 (r312:79147, Dec  9 2011, 20:47:34) 
[GCC 4.4.3] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import rospy
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/vol/corcse/ros-fuerte/x86_64/lib/python2.6/site-packages/ros_comm-1.8.7-py2.6.egg/rospy/__init__.py", line 47, in <module>
    from std_msgs.msg import Header
  File "/vol/corcse/ros-fuerte/x86_64/lib/python2.6/site-packages/std_msgs/msg/__init__.py", line 1, in <module>
    from _Bool import *
ImportError: No module named _Bool
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answered 2012-05-03 04:36:37 -0500

michikarg gravatar image

updated 2012-05-03 04:36:59 -0500

After playing around a bit with ROS and Python3, i basically got ROS messaging running from python2 and 3! A created a ticket and patches, so feel free to test:

https://code.ros.org/trac/ros/ticket/3949

I also had to fix genpy. You can download the lated trunk (already including my patch the fixes your problem with the _Bool import) from github:

https://github.com/ros/genpy

Cheers

Michi

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answered 2012-04-25 06:12:29 -0500

joq gravatar image

To limit confusion for those reading this page, @michikarg and @languitar are discussing useful work for future python3 migration, done in branches of various core ROS components.

ROS Fuerte does not officially support python3.

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1

Thanks, i should have pointed that out at the beginning of my answer.

michikarg gravatar imagemichikarg ( 2012-04-25 20:06:51 -0500 )edit
1

answered 2012-04-25 03:26:44 -0500

michikarg gravatar image

Here is a patch for /opt/ros/fuerte/lib/python2.7/dist-packages/roslib/stacks.py that allows you to import roslib using Python3. Let me know if this worked for you:

http://ias.cs.tum.edu/~kargm/stacks_py3k.patch

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answered 2012-04-25 02:56:16 -0500

michikarg gravatar image

I am one step further now! rospkg is now standalone, so you will have to install it with the correct python-version and user:

  1. Git clone it:

    git clone git://github.com/ros/rospkg.git

  2. Install it using Python3:

    python3.2 setup.py install --user

This basically solved the issue of the rospkg-module not beeing found. However it raises another issue for me when iḿ trying to import roslib:

>>> import roslib
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/opt/ros/fuerte/lib/python2.7/dist-packages/roslib/__init__.py", line 54, in <module>
    import roslib.stacks
  File "/opt/ros/fuerte/lib/python2.7/dist-packages/roslib/stacks.py", line 190
    print "ROS_PATHS", ros_paths, env['ROS_PACKAGE_PATH']

This could be related to missing Python3-support in roslib, so i guess we will have to write some more patches....

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I could also fix that very easily... i will write a patch for it...

michikarg gravatar imagemichikarg ( 2012-04-25 03:04:31 -0500 )edit
0

answered 2012-04-24 23:51:29 -0500

michikarg gravatar image

updated 2012-04-25 20:08:47 -0500

NOTE: ROS Fuerte DOES NOT officially support Python3! Although the following discussion is about work in progress for partial Python3 compatibility!

Hi,

we patched parts of ros core and ros_comm for python3 so basically messaging should be possible.

You just have to set you Pythonpath to roslib and in set your yaml-folder (in case you need it) to the pyyaml you installed using python3:

export PYTHONPATH=$PYYAML_DIR/pyyaml/lib/python3.2/site-packages:/opt/ros/electric/ros/core/roslib/src

After importing roslib in your python-file, you should be able to normally use roslib.load_manifest and code in Python3.

So far i only used it with ROS Electric, but i will install Fuerte quite soon and check if everything works....

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I just installed Fuerte and ended up with "ImportError: No module named rospkg". Since rospack is now standalone, i installed it for Python2 and 3 but this seems not to work either...

michikarg gravatar imagemichikarg ( 2012-04-25 02:41:22 -0500 )edit
1

I'll open a new question for this topic...

michikarg gravatar imagemichikarg ( 2012-04-25 02:43:03 -0500 )edit

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Asked: 2012-04-24 22:02:22 -0500

Seen: 1,652 times

Last updated: May 03 '12