How to get the Column of the Max Value by Row

Assume that our data frame is:

set.seed(5)
df<-as.data.frame(matrix(sample(1:100,12),ncol=3))
df

  V1 V2 V3
1 66 41 19
2 57 85  3
3 79 94 38
4 75 71 58

We can get the index and the name of the max column by row as follows:

colnames(df)[max.col(df,ties.method="random")]

[1] "V1" "V2" "V2" "V1"