[ros-users] 2d numpy arr msgs?

James Bowman jamesb at willowgarage.com
Mon Jun 14 22:52:54 UTC 2010


You can turn the numpy array into a single-channel CV image, then use
cv_bridge to turn it into a message:

msg = CvBridge().cv_to_imgmsg(cv.fromarray(a))

and:

a = numpy.fromarray(CvBridge().imgmsg_to_cv(msg))


On Mon, Jun 14, 2010 at 3:27 PM, Ken Conley <kwc at willowgarage.com> wrote:

> The ROS msg IDL only supports 1D arrays. The reshape approach is the
> correct approach to ensure compatibility in multiple languages.
>
>  - Ken
>
> On Mon, Jun 14, 2010 at 3:23 PM, Floris van Breugel <florisvb at gmail.com>wrote:
>
>> Hi folks,
>>
>> Is there a way to publish 2D numpy arrays as messages (using python)? I
>> went through the numpy tutorial for rospy but it seems to only work for 1D
>> arrays. I suppose one could reshape the 2D array to be 1D, and pass the
>> shape as another message, and then reconstruct it on the other side, but
>> maybe there's a more efficient way to do it? Or that functionality could be
>> added to numpy_msg.py?
>> http://www.ros.org/wiki/rospy_tutorials/Tutorials/numpy
>>
>> Thanks!
>>
>> - Floris
>>
>>
>>
>> --
>> Floris van Breugel
>> Caltech Graduate Student
>> Control and Dynamical Systems
>> (925) 963 8280
>>
>> Wildlife and Landscape Photographer
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>>
>>
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>
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-- 
J.
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