plot.roc for multiclass.roc in pROC package?

r roc auc
AngryPanda picture AngryPanda · Dec 9, 2015 · Viewed 9.3k times · Source

I am trying to plot multiclass ROC curves but I have not found anything fruitful in the pROC package. Here's some start code:

data(iris)
library(randomForest)
library(pROC)
set.seed(1000)
# 3-class in response variable
rf = randomForest(Species~., data = iris, ntree = 100)
# predict(.., type = 'prob') returns a probability matrix
predictions <- as.numeric(predict(rf, iris, type = 'response'))
roc.multi <- multiclass.roc(iris$Species, predictions)
auc(roc.multi)

How do I plot the ROC curves for individual classes?

Answer

Zhang Cheng picture Zhang Cheng · Mar 7, 2017

Check the names of the roc.multi, you should found a name called rocs, which stores individual roc curve info for each classes.

So you can use plot.roc and lines.roc to visualize all of them: 

rs <- roc.multi[['rocs']]
plot.roc(rs[[1]])
sapply(2:length(rs),function(i) lines.roc(rs[[i]],col=i))

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