Search code examples
rdataframematrixapplysapply

R Keep colnames and rownames when using sapply on a matrix

A question was already asked on how keeping colnames in a matrix when applying apply, sapply, etc. here. But I didn't find how to keep the column AND row names of a matrix.

Below an example:

mat = matrix(c(as.character(1:4)), nrow = 2)
colnames(mat) = c( 'col1', 'col2' )
rownames(mat) = c( 'row1', 'row2' )
mat = apply(mat,  2,  function(x) as.numeric(paste(x)))
colnames(mat)
rownames(mat)

Thanks in advance :-)

Solution

  • We can wrap your application in a user-defined function.

    mat_fun <- function(m){
  m2 <- apply(m,  2,  function(x) as.numeric(paste(x)))
  colnames(m2) <- colnames(m)
  rownames(m2) <- rownames(m)
  return(m2)
}

mat_fun(mat)
#      col1 col2
# row1    1    3
# row2    2    4