Message-ID: <1051904469.3eb2c9d516257@webmail.fas.harvard.edu>
Date: 2003-05-02T19:41:09Z
From: langensk@fas.harvard.edu
Subject: Creating Dummy Variables with if else phrase
Dear All,
I want to do 52 state dummy variables. In order to make it easier for me, I
thought of using the below commands. (x is the vector with state variables,
matrix will correspond to the dummy variables)
x <- c(1,2,NA,4)
matrix <- matrix(0,nrow=4,ncol=4)
for (i in 1:4) {
if (is.real(x[i])) {
matrix[i,x[i]] <- 1 } else {
matrix[i,] <- rep(NA,4)
}
}
This gives me the following matrix:
1 0 0 0
0 1 0 0
0 0 0 0
0 0 0 1
But I want it to look as follows:
1 0 0 0
0 1 0 0
NA NA NA NA
0 0 0 1
I want the forth row to be NA, but it is unchanged, i.e., 0. The second "else"
phrase does not seem to work, and I cannot see what is wrong.
I would be very grateful for your help.
Regards, Sophie