How to pass a function to julia Gadfly Theme parameter

Question

I make a plot like this:

plot(
  layer(x=sort(randn(1000),1), y=sort(randn(1000),1), Geom.point),
  layer(x=[-4,4], y=[-4,4], Geom.line(), Theme(default_colo         


        

Answer 1

For those like me trying to solve this problem more recently, I discovered that the best way to get rid of that pesky white ring is through the theme setting highlight_width=0pt

for example

plot(x=rand(10),y=rand(10),Theme(highlight_width=0pt))

I had some additional themes in the below image

Answer 2

The argument name turns out to be discrete_highlight_color...

It should be a function that modifies the colour used for the plot, typically by making it lighter (a "tint") or darker (a "shade"). In our case, we can just ignore the current colour and return black.

using Color
using Gadfly
plot(
  layer(
    x = sort(randn(1000),1), 
    y = sort(randn(1000),1), 
    Geom.point,
    # Theme(highlight_width=0.0mm) # To remove the border
    Theme( discrete_highlight_color = u -> LCHab(0,0,0) )
  ),
  layer(
    x = [-4,4], 
    y = [-4,4], 
    Geom.line(), 
    Theme(default_color=color("black"))
  )
)

To find the correct argument, I first typed

code_lowered( Theme, () )

which gives the list of arguments, and then

less( Gadfly.default_discrete_highlight_color )

which shows how the default value is defined.