legend improvements

[cnrrobertson]

Describe how it works in R's ggplot2

• Legends work with categorical variables, Example: ggplot(diamonds, aes(x=x,y=y,color=color)) + geom_point()
• Multiple legends
  • For multiple aes specs. Example: ggplot(diamonds, @aes(x=Depth, y=Price)) + geom_point(@aes(color=Carat)) + geom_point(@aes(color=Table))
  • Generate a legend for aes with multiple features (such as both size and color), Example: ggplot(diamonds, aes(x=x,y=y,color=color, size=carat)) + geom_point()

[rdboyes]

Can you elaborate on the first point? I think legends already work with categorical variables, e.g.

ggplot(penguins, @aes(x=bill_length_mm,y=bill_depth_mm,color=island)) + geom_point()

[cnrrobertson]

You're right! I didn't realize. But I think I've stumbled on a bug - it doesn't work when the DataFrame column for color is a CategoricalVector (apparently most/all? datasets from RDatasets.jl have categorical columns stored in that format). But I think this an upstream issue in Makie:

ERROR: MethodError: no method matching to_color(::CategoricalValue{String, UInt8})

Closest candidates are:
  to_color(::Makie.Palette)
   @ Makie ~/.julia/packages/Makie/iRM0c/src/conversions.jl:845
  to_color(::Symbol)
   @ Makie ~/.julia/packages/Makie/iRM0c/src/conversions.jl:854
  to_color(::Makie.Scene, ::Any, ::Makie.Cycled)
   @ Makie ~/.julia/packages/Makie/iRM0c/src/makielayout/blocks/axis.jl:695
  ...

You can recreate with

using CategoricalArrays
penguins.island = categorical(penguins.island)
ggplot(penguins, @aes(x=bill_length_mm, y=bill_depth_mm, size=island)) + geom_point()

Alternatively, we could try to convert those columns to strings when plotting?

[rdboyes]

It's strange - I actually convert the Strings to CategoricalVectors under the hood already. Should be an easy fix I think, I'm sure I'm just missing a check somewhere

[rdboyes]

This is fixed in 0.8.0! Multiple legends are still a work in progress though

[Jigyasu4indp]

In the geom_tile example (link: https://tidierorg.github.io/TidierPlots.jl/latest/examples/generated/geoms/geom_tile/), the color legend is missing. How can I add it?

[rdboyes]

Finally made progress on this!

ggplot(penguins) + 
  geom_point(aes(x = :bill_length_mm, y = :bill_depth_mm, size = :bill_depth_mm, color = :sex)) + 
  scale_size(range = [5, 15], name = "Bill Depth") + 
  scale_color_discrete(palette = :julia, name = "Sex")

[rdboyes]

I'm going to close this as complete - the second bullet does not work even in R ggplot, and seems like a use case we would want to discourage

[Jigyasu4indp]

I encountered an issue with the following code:

ggplot(gfgt, @aes(x = lon, y = lat, z = co2)) +
  geom_tile() + 
  scale_color_discrete(palette = :tab20, name = "co2") +
  theme_light()

Attributes with 5 entries:
  Axis => Attributes with 13 entries:
    backgroundcolor => transparent
    bottomspinevisible => false
    leftspinevisible => false
    rightspinevisible => false
    topspinevisible => false
    xgridcolor => (:black, 0.07)
    xlabelpadding => 3
    xminorticksvisible => false
    xticksvisible => false
    ygridcolor => (:black, 0.07)
    ylabelpadding => 3
    yminorticksvisible => false
    yticksvisible => false
  Axis3 => Attributes with 9 entries:
    xgridcolor => (:black, 0.07)
    xspinesvisible => false
    xticksvisible => false
    ygridcolor => (:black, 0.07)
    yspinesvisible => false
    yticksvisible => false
    zgridcolor => (:black, 0.07)
    zspinesvisible => false
    zticksvisible => false
  Colorbar => Attributes with 3 entries:
    spinewidth => 0
    ticklabelpad => 5
    ticksvisible => false
  Legend => Attributes with 2 entries:
    framevisible => false
    padding => (0, 0, 0, 0)
  textcolor => gray50

When I run this code as-is, it doesn't work as expected (i.e., it doesn't produce the desired plot). However, if I comment out the scale_color_discrete line:

ggplot(gfgt, @aes(x = lon, y = lat, z = co2)) +
  geom_tile() +
  # scale_color_discrete(palette = :tab20, name = "co2") +
  theme_light()

the plot is generated, but the color legend is missing. Could you please fix the color legend for geom_tile plots?