Plot entity state over time

[kopytjuk]

I have a message with multiple entities with each holding a state (e.g. location in cartesian plane, e.g. e[i].x and e[i].y). Each entity has an id, i.e. e[i].id.

My message looks like time, [e_1, e_2, ..., e_n]. The array length can change over time. The order of the entities is not determenistic, new entities (with new id can spawn).

My wish is to plot the x coordinate over time with a different color for each unique id.

Can I visualize such data in PlotJuggler? I played around with the UI and could not find a setting or set up the plot. If it is not possible how would one implement such functionality in the repository? I would love to contribute!

[facontidavide]

I need to know more about your data source. ROS? CSV? custom?

I can hardly understand how to reproduce and fix this without a tangible example.

In general, anyway, the solution is to create your own message parser.

[kopytjuk]

You are right, I should be more explicit. I use ROS and my application's message definition is the following:

Entity message:

int64  id
geometry_msgs/Point position

Entity message, this one I want to visualize over time:

std_msgs/Header header
Entity[] entities

I want to visualize the position (e.g. x) of unique entities (by id) over time.

[kopytjuk]

Currently we can plot it, but the x attribute is always over the ith element from Entity[] entities list. I.e. I want to group by id and plot afterwards.

[facontidavide]

In this case, I am afraid that you need to create your custom parser: https://github.com/PlotJuggler/plotjuggler-ros-plugins/tree/development/plugins/ros1_parsers

[facontidavide]

Note that the implementation is trivial, but being this a specific ROS message and not a generic one, such change will never be included in mainline repo.

[facontidavide]

This might be a good example similar to what you need

https://github.com/PlotJuggler/plotjuggler-ros-plugins/blob/development/plugins/ros1_parsers/jointstates_msg.h