naLast: Move All 'NA' Values to the End of the Rows or Columns of a...
In mrdwab/SOfun: Functions From Answers to R Questions on Stack Overflow

Description Usage Arguments Value Author(s) References Examples

Moves all of the NA values in the rows or columns of a matrix to the end of the respective rows or columns.

1	naLast(inmat, by = "row", outList = FALSE, fill = NA)

`inmat`	The input matrix.
`by`	Should be either `"row"` or `"col"`, depending on if you want to shift non-`NA` values left or up.
`outList`	Logical. Do you just want a `list` of the non-`NA` values? Defaults to `FALSE`.
`fill`	While you're at it, do you want to replace `NA` with some other value?

Either a matrix with the same dimensions as the input matrix or a list with the same number of rows or columns as the input matrix (depending on the choice made in by).

Ananda Mahto

http://stackoverflow.com/q/23008142/1270695

set.seed(1)
m <- matrix(sample(25, 20, TRUE), ncol = 4,
            dimnames = list(letters[1:5], LETTERS[1:4]))
m[sample(prod(dim(m)), prod(dim(m)) * .6)] <- NA

m

naLast(m, by = "row")
naLast(m, by = "col")
naLast(m, by = "col", outList = TRUE)