For the following data set
> data
x1 x2 x3
1 1 0 0
2 0 1 0
3 0 0 1
4 0 0 1
5 1 0 0
6 0 1 0
7 1 0 0
8 0 1 0
9 0 0 1
10 1 0 0
I would like to create new variable z such that it takes 1 if x1=1, 2 if x2=1 and 3 if x3=1, z will look like z=c(1,2,3,3,1,2,1,2,3,1).
Any help is appreciated
Assuming there will be only one 1 in a given row as shown in the data shared, we can use max.col
data$z <- max.col(data)
data
# x1 x2 x3 z
#1 1 0 0 1
#2 0 1 0 2
#3 0 0 1 3
#4 0 0 1 3
#5 1 0 0 1
#6 0 1 0 2
#7 1 0 0 1
#8 0 1 0 2
#9 0 0 1 3
#10 1 0 0 1
In case of multiple 1's in a given row explore the ties.method in ?max.col which gives an option to get "first" or "last" 1.
If we want to return 0 if all the row values are 0 we can do :
data$z <- max.col(data) * +(rowSums(data == 1) > 0)
1 with max.col(data). But the output should be 0 @Ronak