[R] how to add a derived column to a data frame?

[Petr Savicky]

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.