Add support of plotting individual variables inside a message

[nyxaria]

Hello, I'd like to say that this is a super awesome program!

There is one thing that I would love if you could support though: plotting individual variables from within messages.

For example:

~/catkin_ws/src$ rosshow /joint_states/effort[2] Topic /joint_states/effort[2] does not appear to be published yet.

Now, /joint_states message type is not supported, but the variable /joint_states/effort[2] points to an Int message, which should be supported right?

What do you think? :D

[dheera]

This is an interesting idea. For message types that are part of ROS, this is probably doable.

However, I'm not too sure though how to implement it in the case of a custom message, e.g. a message with type custom_msgs/CustomMessage that has a field "float32 foo" that is plottable, which I presume would be a really nice use case of what you suggested. If anyone can offer tips on implementing this cleanly that would be great!

[nxdefiant]

rostopic can do that, e.g.

# rostopic echo -n 1 /odom/twist/twist/angular/z                                                                                                                                                                                                              
2.08793471184e-43
---

works with any type.

[nxdefiant]

Update: Looks like they do it manually, see rostopic/init.py#L890

we should be able to use that.

[nxdefiant]

I did a proof of concept implementation in my fork, steeling from rostopic. A bit hackish maybe, but calls like rosshow /odom/twist/twist/angular/z should work. Array indexing not yet.

[nxdefiant]

Any feedback?

[nyxaria]

Super awesome- Thanks for your fork! I've not the time right now to install ros on my machine a-new, since I stopped working with it a few months ago. However, I will do so in the near future.

[dheera]

Thanks @nxdefiant ! I'll take a look at this soon. Sorry for the delays in maintaining this.