[FR] - Add na.pad argument in row/colDiffs()

[Eluvias]

It would be nice to have this feature when rowDiffs() / colDiffs() is used within intermediate calculations that require positional matching.

x <- matrix(1:27, ncol = 3)

library(matrixStats)
colDiffs(x)
     [,1] [,2] [,3]
[1,]    1    1    1
[2,]    1    1    1
[3,]    1    1    1
[4,]    1    1    1
[5,]    1    1    1
[6,]    1    1    1
[7,]    1    1    1
[8,]    1    1    1

With na.pad set to TRUE

library(xts)
xts::diff.xts(x, na.pad = TRUE)
      [,1] [,2] [,3]
 [1,]   NA   NA   NA
 [2,]    1    1    1
 [3,]    1    1    1
 [4,]    1    1    1
 [5,]    1    1    1
 [6,]    1    1    1
 [7,]    1    1    1
 [8,]    1    1    1
 [9,]    1    1    1

Also, on a different note I think dim. argument is not coerced to integer as intended when the dim. is given manually. I believe the expression dim <- as.integer(dim.) was placed there to enforce it, but it's not passed into C call:

 body(colDiffs)
{
    dim <- as.integer(dim.)
    .Call(C_rowDiffs, x, dim., rows, cols, as.integer(lag), as.integer(differences), 
        FALSE)
}