Extract NULL column in a matrix e.g. matrix[,-NULL]
Try: aa[, !seq(ncol(aa)) %in% NULL]
On 2/11/07, Pierre Lapointe <pierrelap at gmail.com> wrote:
Hello,
I need to remove columns in a matrix. The number of columns varies from 0
to n. I can't figure out how to specify the zero case.
aa <-matrix(runif(5^2),5,5)
#remove column 3
aa[,-3]
#remove no column
aa[,-NULL]
Error in -NULL : invalid argument to unary operator
I know I could use ifelse, but it would complicate my model a lot. Is there
a direct way to specify that the number of columns to remove is 0?
Pierre Lapointe
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