Positioning in violin plot

General Usage
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1

I would like to add ground truth values to a violin plot. So suppose I knew that for my category "a" the true value is 2.0 and I have a violin plot, I could use scatter like so:

violin(repeat(["a", "b", "c"], outer=100), randn(300), leg=false)
scatter!([(0.5, 2.0)])

Now I used an absolute value (0.5) to determine the x-position of the relevant violin plot which works in this toy example. Unfortunately, with my data, the violin plots use a different spacing, so I cannot just use 0.5, 1.5, 2.5 ... as the x-positions.

How can I determine the correct x-position to add my ground truth value centered in the corresponding violin plot regardless of the shape of the data?

Thanks

Simon

2

One method might be to exploit the fact that scatter! can use a vector of strings for the x-positions. So something like this:

using StatsPlots
gr()
myviolin = violin(repeat(["a", "b", "c"], outer=100), randn(300), leg=false)
scatter!(["a", "b", "c"], [2,1,0], markersize=10) # note the x-argument
savefig(myviolin, "violin_with_markers.png")

violin_with_markers

Does this work for your case?

1 Like
3

It does! What a simple and elegant solution, thanks a lot!