foxplot

Plot time-series data from newline-delimited JSON.

Foxplot stands for "Frequent Observation diXionary plots". Frequent observations arise from the project's initial use case with robot control loops, while dictionaries are a common weakly-typed self-describing format (used e.g. in the GitHub REST API, robot logging, ...).

Installation

pip install foxplot

Usage

Interactive mode

In interactive mode, you can explore the data in data (tab completion works) and plot it using the foxplot function:

$ foxplot -i upkie_2023-05-03-103245.mpack
Python 3.8.10 (default, Mar 13 2023, 10:26:41)
Type 'copyright', 'credits' or 'license' for more information
IPython 8.0.1 -- An enhanced Interactive Python. Type '?' for help.

In [1]: foxplot(
   ...:     [
   ...:         data.observation.servo.left_knee.torque,
   ...:         data.observation.servo.left_wheel.torque,
   ...:     ],
   ...:     right=[
   ...:         data.observation.servo.left_knee.velocity,
   ...:         data.observation.servo.left_wheel.velocity,
   ...:     ],
   ...: )
New tab opened in your web browser! The command line is to produce it directly is:

foxplot upkie_2023-05-03-103245.mpack -l /observation/servo/left_knee/torque /observation/servo/left_wheel/torque -r /observation/servo/left_knee/velocity /observation/servo/left_wheel/velocity

Plotting from files

• JSON: foxplot my_data.json -l /observation/cpu_temperature
• MessagePack: foxplot my_data.mpack -l /observation/cpu_temperature

Design notes

• Foxplot prioritizes ease-of-use (interactive mode) over performance

Tips

• For Zsh users:

zstyle ":completion:*:*:foxplot:*" ignored-patterns "^*.(json|mpack)"

See also

• µPlot's performance was a key enabler for this project.
• rq, a tool to manipulate streams of records in various formats.