CODEWITHSUNDEEP
rggplot2roc
zesla
zesla

Reputation: 11833

Set line alpha when plotting multiple roc curves (in same color) with plotROC

I'm ploting my ROC curves with plotROC. Below is the example code. I need to plot multiple roc curves with the same color. I found I need to use alpha in aes. Now I need to control the transparency of my curves. Using alpha in geom_roc is not working. Does anyone knows what I can do? Thanks a lot. 

D.ex <- rbinom(50, 1, .5)
rocdata <- data.frame(D = c(D.ex, D.ex), 
                   M = c(rnorm(50, mean = D.ex, sd = .4), 
                         rnorm(50, mean = D.ex, sd = 1)), 
                   Z = rep(c('A', 'B', 'C', 'D', 'E'), each=20) )
library(plotROC)
ggplot(rocdata, aes(m=M, d=D, alpha=Z)) + 
            geom_roc(cutoffs.at = NULL, n.cuts=0, color='blue')+
            theme(legend.position="none")

Upvotes: 0

Views: 499

Answers (1)

pogibas
pogibas

Reputation: 28369

For plotROC::geom_rec you have to set alpha with linealpha argument (not within aes). But for this to work you also need to specify line group. Usually in ggplot2 it's done with group = Z, but in geom_rec it doesn't work. Quick solution would be to set color by Z (color = Z) and with scale_color_manual set same color.

library(plotROC)
ggplot(rocdata, aes(m = M, d = D, color = Z)) + 
    geom_roc(cutoffs.at = NULL, n.cuts = 0, linealpha = 0.5) +
    scale_color_manual(values = rep("black", length(unique(rocdata$Z)))) +
    theme(legend.position = "none")

enter image description here

Upvotes: 2

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