How to create an empty matrix in R?

Solution 1:

The default for matrix is to have 1 column. To explicitly have 0 columns, you need to write

matrix(, nrow = 15, ncol = 0)

A better way would be to preallocate the entire matrix and then fill it in

mat <- matrix(, nrow = 15, ncol = n.columns)
for(column in 1:n.columns){
  mat[, column] <- vector
}

If you don't know the number of columns ahead of time, add each column to a list and cbind at the end.

List <- list()
for(i in 1:n)
{
    normF <- #something
    List[[i]] <- normF
}
Matrix = do.call(cbind, List)