在 R 中更改 ROC 上的刻度线

Question

library(ROCR)
data(ROCR.simple)
pred = prediction( ROCR.simple$predictions, ROCR.simple$labels)
roc.perf = performance(pred, measure = "tpr", x.measure = "fpr")
plot(roc.perf)

How can I change the scale of the x and y axis to be a percent instead of decimal?

Note: I would like to use a base R solution, or use a solution available in the ROCR package. I am unable to access the GGPLOT2 library, since I am on a closed network.

Answer 1

If you look at the code for .plot.performance (which is used to plot your prediction), they store the x and y values under @x.values and @y.values.

So you can do it like this:

plot(roc.perf@x.values[[1]]*100,roc.perf@y.values[[1]]*100)

To get % as ticks, do:

plot(roc.perf@x.values[[1]],roc.perf@y.values[[1]],
xaxt="n",yaxt="n",type="l",ylab="True Positive Rate",
xlab="False Positive Rate")

TICKS=seq(0,1,by=0.2)
LABELS=paste0(100*TICKS,"%")
axis(side=2,at=TICKS,label=LABELS)
axis(side=1,at=TICKS,label=LABELS)