Chartjs-pl

Purpose

This is the start of using Chart.js graphing for notebooks with polars as a backend. It gets inspiration from plotly but I like the look of Chart.js graphs more than Plotly plus, supposedly, the canvas based Chartjs should perform better than svg based plotly. Also, I sometimes make small React webapps that natively use Chart.js so I'd like my notebook output to look consistent with those. Lastly, I couldn't get ipychart to work in my environment and it gives an excuse to make a charting library with polars as backend with no pandas.

Status

I struggled with importing the main chart.js plus plugins from a CDN using IPython calls to Javascript for awhile and eventually used vite to publish a bundled version of Chart.js with zoomPlugin and autocolors built in as a single umd.js file. That is here.

With that done, we can run calls to

Javascript(
    """
require(['https://www.unpkg.com/[email protected]/dist/chartBundle.umd.js'], function(chartjs) {
    var ctx = document.getElementById("%s");
    chartjs.Chart.register(chartjs.zoomPlugin);
    new chartjs.Chart(ctx, %s);
    })"""
    % (this_id, cfg)
)

Right now there's a bar function with some options exposed but it already needs some refactoring before more things are added and a thought to the future of making multiple graph types in one.

Near term goals

1. Refactor and expose scatter, line charts
2. Create functions for generated graphs, ie histograms (bar), ecdf (line), etc
3. Expose more chart customizations/options
4. Wrap all functions in a class which is registered to pl.DataFrame namespace for df.cx.scatter(...) syntax.
5. Publish as pip installable package.

Medium term goals

1. Expose mixed graphs, (ie lines and bars on same chart)
2. Incorporate animation as a dimension similar to plotly

Aspirational idea(s) aka need help to do these

1. use mathbox.js for webgl 3d graphs (maybe this is new library)
2. connect wasm polars to Python polars to prevent serialization