Get names of column with max value for each row

Question

i need your help, i have a data frame like this

int x  y  z
1   0  1  0
2   1  0  0
3   0  0  1

and the result that i need must be like thi

Answer 1

You can use max.col:

dat$newcol <- names(DF)[-1][max.col(DF[-1])]

This gives

  int x y z newcol
1   1 0 1 0      y
2   2 1 0 0      x
3   3 0 0 1      z

Answer 2

A solution to this similar question.

tdf <- data.frame(
  A = c(1,1,0,0),
  B = c(0,0,1,0),
  C = c(0,0,0,1)
)

library(magrittr)

tdf %>%
  lapply(sum) %>%
  (function(x){
    a <- c()
    for(i in 1:length(x)){
      a <- c(a, rep(names(x[i]), x[i]))
    }
    return(a)
  })

Answer 3

I'm sure there are plenty of ways, but here's one:

samples <- read.table(text="int x  y  z
1   0  1  0
2   1  0  0
3   0  0  1",
header=TRUE)

#  int x y z
#1   1 0 1 0
#2   2 1 0 0
#3   3 0 0 1

data.frame(
 samples[1],
 letter=colnames(samples[-1][apply(samples[-1],1,which.max)])
)

#  int letter
#1   1      y
#2   2      x
#3   3      z