Plots.jl: [FR] `legend = false` should not hide colorbar

[mkborregaard]

Right now legend = false will also hide the colorbar, leading to the awkward legend = false, colorbar = true. I don't think we ever want the current behaviour. legend and colorbar should simply be separate IMHO

[isentropic]

At this point it has the default value colobar = :legend that copies the behavior of the legend. As per https://github.com/JuliaPlots/Plots.jl/blob/fff8f84acf62550f068810970e146e085264c9c5/src/arg_desc.jl#L107

I guess we should set the default value to be colorbar = :right should it be the case though?

[isentropic]

Personally, I think the current behavior is very much reasonable, I wonder what others think

[mkborregaard]

The colorbar already has sensible defaults - it's being shown if you ask for it explicitly, if you have a heatmap or a surface, or if you have color encoding in a variable with line_z or marker_z. I don't see why legend should override those sensible defaults, to be honest.

[mkborregaard]

Consider this case:

plot(rand(4,5), line_z = (1:5)')

plot(rand(4,5), line_z = (1:5)', legend = false)

BTW I think maybe

┌ Warning: Multiple series with different color share a colorbar. Colorbar may not reflect all series correctly.
└ @ Plots ~/.julia/packages/Plots/JKY3H/src/backends/gr.jl:491

should have been an @info not a warning?

[isentropic]

Good point, this is a very good example.

Additionally, would we want no legend if colorbar needs to be drawn?
That is, the default behaviour should be no legend in the presence of colorbar?

[daschw]

Additionally, would we want no legend if colorbar needs to be drawn?
That is, the default behaviour should be no legend in the presence of colorbar?

No, I don't think so. For heatmaps and contours legends are already suppressed automatically and for other cases (see Michael's first plot) it could make sense to have a legend. In that case I would leave removing the legend to the users.

[mkborregaard]

Agree with Daniel. The issue is also there with composite plots

(e.g. if I want to combine a heatmap with a polygon such as in the below example), but that should also be solved by unlinking them.

[daschw]

Nice plot! What does it show?

[mkborregaard]

Species richness of the world's 6000 species of amphibians :-)