r - How to draw multiple roc curves with confidence interval in pROC?

Question

This code can draw a roc curve with confidence interval:

ciobj <- ci.se(obj, specificities=seq(0, 1, l=25))
dat.ci <- data.frame(x = as.numeric(rownames(ciobj)),
                     lower = ciobj[, 1],
                     upper = ciobj[, 3])

ggroc(obj) + theme_minimal() + geom_abline(slope=1, intercept = 1, linetype = "dashed", alpha=0.7, color = "grey") + coord_equal() + 
  geom_ribbon(data = dat.ci, aes(x = x, ymin = lower, ymax = upper), fill = "steelblue", alpha= 0.2) + ggtitle(capture.output(obj$ci))

and this code can draw multiple roc curves together

roc.list <- roc(outcome ~ s100b + ndka + wfns, data = aSAH)
g.list <- ggroc(roc.list)
g.list

but I cant combined them together:

ggroc(roc.list) + theme_minimal() + geom_abline(slope=1, intercept = 1, linetype = "dashed", alpha=0.7, color = "grey") + coord_equal() + 
  geom_ribbon(data = dat.ci, aes(x = x, ymin = lower, ymax = upper), fill = "steelblue", alpha= 0.2) + ggtitle(capture.output(obj$ci))

it will return an error:

Answer 1

There might be a more elegant way to do that, but here is what works for me anyway:

library(pROC)
roc.list <- roc(outcome ~ s100b + ndka + wfns, data = aSAH)


ci.list <- lapply(roc.list, ci.se, specificities = seq(0, 1, l = 25))

dat.ci.list <- lapply(ci.list, function(ciobj) 
  data.frame(x = as.numeric(rownames(ciobj)),
             lower = ciobj[, 1],
             upper = ciobj[, 3]))

p <- ggroc(roc.list) + theme_minimal() + geom_abline(slope=1, intercept = 1, linetype = "dashed", alpha=0.7, color = "grey") + coord_equal()

for(i in 1:3) {
  p <- p + geom_ribbon(
    data = dat.ci.list[[i]],
    aes(x = x, ymin = lower, ymax = upper),
    fill = i + 1,
    alpha = 0.2,
    inherit.aes = F) 
  } 

p

I had to remove the title, and add the argument inherit.aes = F.

And the result below :