Here is my dataframe:
ID <- 1:4
var1 <- c("yes","no","yes","no")
var2 <- c("no","no","yes","no")
var3 <- c("yes","yes","no","no")
data <- data.frame(ID, var1, var2, var3)
I want to replace all of the yes by 1 and no by 0 in order to have such a table below
ID var1 var2 var3
1 1 1 0 1
2 2 0 0 1
3 3 1 1 0
4 4 0 0 0