R - apply function - Deactivation of matrix conversion -

is possible deactivate as.matrix() conversion of apply()?

in r documentation , in previous posts @ stack overflow, not find flags solve problem.

example: selection of multiple sub matrices matrix using apply().

problem: apply() function automatically converts results matrix. leads 1 big matrix containing results.

code:

#mat contains data, m desired column selections   mat  <- matrix(c(1,2,3,4,                  2,3,4,1,                  2,4,3,1,                  3,4,2,1)                  ,nrow = 4)  colnames(mat) <- c(1,2,3,4)  m <- matrix(c(1,2,               3,4)               ,nrow = 2)     #selects first 2 , last 2 columns of mat #returns matrix of both results (connected rbind) #instead of list of 2 matrices l <- apply(m,1,function(r)mat[,r]) 

it clear workaround example simple (select rows manually), trying write generic code bigger data sets.

convert m data.frame , use lapply:

lapply(data.frame(m), function(r) mat[,r]) $x1      1 2 [1,] 1 2 [2,] 2 3 [3,] 3 4 [4,] 4 1  $x2      3 4 [1,] 2 3 [2,] 4 4 [3,] 3 2 [4,] 1 1