histogram colored bars

[chriddyp]

as reported in https://community.plot.ly/t/coloring-selected-range-in-histogram/5619/1

it looks like marker.color is documented in the schema

but i couldn't get it to work

[etpinard]

Here's one that works: http://rickyreusser.com/plotly-mock-viewer/#histogram_colorscale

But really, how is marker.color supposed to work for histogram where x.length in general doesn't match marker.color.length?

[alexcjohnson]

right, we had already discussed removing histogram colorscale functionality, at least as implemented now - see #420 (comment) and #1500 - because it only works accidentally and depends on you explicitly making the correspondence between bins and color values. But I could certainly see supporting a histogram-specific colorscale functionality, where probably you would specify it similarly to #histogram_colorscale but instead of a color array you'd connect the color to either the x or the y values.

@chriddyp the issue with doing it the way you tried is, as @etpinard alluded, the values you want to color don't match up with the values you're binning... so it's redundant (and ambiguous - what happens when two values that get binned together have different colors?) and also generally you'd want to color by either the bin value or the bin height rather than the pre-binned values.

[chriddyp]

but instead of a color array you'd connect the color to either the x or the y values.

Yeah, that sounds right. For more context, they would likely be using this to make these types of interactions (currently made with a bar chart):

[jonmmease]

If marker.color is specified as an array of numbers then perhaps an aggregate function from the transform framework (count, sum, mean, etc.) could be specified (e.g. marker.coloragg) to be applied prior to mapping the result to a final color using marker.colorscale.

In this case, color=y with coloragg='count' would be equivalent to coloring by bar height and color=y with coloragg='mean' would be equivalent to coloring by bar position. But lots of other interesting possibilities would be available as well, like color=z with coloragg='median' to color by the median of some other data array z.

@chriddyp @alexcjohnson @etpinard

[gvwilson]

Hi - this issue has been sitting for a while, so as part of our effort to tidy up our public repositories I'm going to close it. If it's still a concern, we'd be grateful if you could open a new issue (with a short reproducible example if appropriate) so that we can add it to our stack. Cheers - @gvwilson