Plotting dataΒΆ

There is an utility which plots any topic or set of topics, in real-time. It is quite similar to (and inspired by) both rqt_plot in ROS and the Arduino IDE serial plotter (by the way, did you know it?). It is contained in the file To use it:

  1. Ensure that you have the pyqtgraph Python module installed.
  2. Open the file. You should change the top lines. The variable TIME_SPAN sets the length of the plot (it rolls to the left, and TIME_SPAN sets how much time a specific data point will stay on the graph before disappearing). TOPICS is a list of topics that you want to graph. All topics should only contain a single number to be graphed (say, the temperature or the atmospheric pressure).
  3. Save the file.
  4. Run the master node and any other nodes, as usual.
  5. When you wish to start plotting data, execute (python or similar)
  6. The script should show a window plotting the data in the specified topics.

See below for an image. Green is real-time barometer data. Red is the same data, processed by a 15-point rolling average.