conditional divison dividing the column with some condition

Question

CMT <- c(1,1,2,3,3,4,4,5,5)
DV <- c(10,10,20,30,30,40,40,50,50)
df <- data.frame(DV,CMT)

I want to divide the values of DV by 10 when CMT is 4.

Answer 1

you can use ifelse

df$DV <- ifelse(df$CMT == 4, df$DV / 10 , df$DV)

df
  DV CMT
1 10   1
2 10   1
3 20   2
4 30   3
5 30   3
6  4   4
7  4   4
8 50   5
9 50   5