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Publish nan to a jointState topic

asked 2017-11-12 16:04:51 -0600

Tanvir gravatar image

updated 2017-11-13 02:29:51 -0600

gvdhoorn gravatar image

Hi, I want to publish a jointState message from terminal with NaNs as the values inside some of its fields. Is there a way I can do that.

If I do

rostopic pub -r 2 /test sensor_msgs/JointState "header:
  seq: 0
  stamp: {secs: 0, nsecs: 0}
  frame_id: '/test'
name: ['l', 'r']
position: [0.0, 0.0]
velocity: [0.0, 0.0]
effort: [nan, nan]"

I get the following error

Unable to publish message. One of the fields has an incorrect type:
  <class 'struct.error'>: 'required argument is not a float' when writing '/test'

Thanks.

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answered 2017-11-13 02:26:43 -0600

gvdhoorn gravatar image

updated 2017-11-13 02:29:18 -0600

ROS uses YAML for this, and according to the YAML 1.1 Reference card the value should be .NAN (all caps, with the dot):

Language Independent Scalar types:
  ...
  [ .inf, -.Inf, .NAN ]    : [ Infinity (float), Negative, Not a number ]

The following seems to work for me:

rostopic pub -r 1 /some_topic std_msgs/Float64 '.NAN'
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Asked: 2017-11-12 16:04:51 -0600

Seen: 463 times

Last updated: Nov 13 '17