Custom ordinal color schemes

[filipkis]

Hi,

I would like to be able to somehow specify a custom color scheme so I can create my charts with our brand colors. As far as I saw from documentation and digging through the source code, there is no way to specify a custom scheme. On can use interpolate option, but that works only when there is a range, so not with ordinal scales.

My suggestion would be that you check if scheme is an array or function and then threat it as custom color scheme, otherwise it behaves as it does now.

[Fil]

related: #630

We want to find a way to register schemes; for example maybe something like

Plot.registerScheme({ "rainbow-company" : { ordinal: ["#ef3550", "#f48fb1", "#7e57c2", "#2196f3", "#26c6da", "#43a047", …] } })

would return an instance of Plot that knows about this new scheme.

For ordinal color scales you can already specify

color: { range: ["#ef3550", "#f48fb1", "#7e57c2", "#2196f3", "#26c6da", "#43a047", …] }

but it's not exactly the same as an ordinal scheme.

[mbostock]

You can set the color.range option for a custom ordinal color scheme.

Plot.plot({
  color: {
    range: ["#36a2eb", "#ff6384", "#ff9f40", "#ffcd56", "#4bc0c0", "#9966ff", "#c9cbcf"],
    legend: true
  },
  marks: [
    Plot.dot(penguins, {x: "culmen_length_mm", y: "culmen_depth_mm", stroke: "species"})
  ]
})

For ordinal scales, the color.scheme option is merely shorthand for a built-in range; you can always specify the range explicitly yourself if desired.

[filipkis]

Thank you!