ENH: scatter plot support for colormap #30
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Looks good. One concern I have is that the names of matplotlib colormaps do not correspond to the names of vega schemes, but there's not really any easy way around that. |
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can we for all those params support both strings and |
I'd lean toward no. I think the main benefit of this API is the ability to create charts that basically work on multiple backends. If we start supporting altair-specific extensions of the core API, then that flexibility goes away, and it may not be apparent to users when they have created a chart that will no longer render with one of the other backends. |
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@jakevdp how would you like to proceed on this? |
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Let's go ahead and apply colormap directly to scheme as here. Not a perfect solution, but I think it's the best thing that can be done easily at this point. First tests and a couple minor changes. |
| raise ValueError("'c' should be defined for using 'colormap'") | ||
| encodings["color"] = alt.Color( | ||
| encodings["color"], scale=alt.Scale(scheme=kwargs.get("colormap")) | ||
| ) |
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Let's put this in the if c is not None block above, so that colormap just has no effect unless c is defined.
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I was doing so, to avoid touching columns = list(set(encodings.values())). Once this block goes up. list(set(encodings.values())) would have to be tweaked to extract value > shorthand > field
See: pandas.DataFrame.plot.scatter
If this looks good, I'll update tests.