how to add a derived column to a data frame?
On Sun, Jan 16, 2011 at 03:01:49PM +0800, r-help wrote:
I have a data frame with 10 columns: A:J and I want to have the output as a data frame with 11 columns, the value of 11th column is?? for each row, if any column can be divided by 13, then the 11th column has a values of 1, otherwise, it has a value of 0. How to do that? input is a=matrix(1:10000,1000,10) dimnames(a)=list(NULL,LETTERS[1:10])
I am sorry for an error in the previous solution for a general matrix. It should be, for example x <- as.numeric(rowSums(a %% 13 == 0) != 0) b <- cbind(a, x) or x <- (rowSums(a %% 13 == 0) != 0) + 0 Petr Savicky.