makeNd: Ensure/collapse an array into 'n' dimensions and restore the...
In arrayhelpers: Convenience Functions for Arrays

Description Usage Arguments Details Value Author(s) Examples

nameNd ensures a given number of dimensions: If a has less than N dimensions, new dimensions of length 1 are appended. If a has more than N dimensions, the supernumerary dimensions are collapsed onto the last dimension.

Attributes old.dim and old.dimnames are used by default. restoredim is the inverse of makeNd.

makeNd(a, N)

restoredim(
  a,
  old = NULL,
  n = 1L,
  ...,
  usedim = TRUE,
  fromend = FALSE,
  drop = FALSE
)

`a`	an array (matrix, vector)
`N`	the desired number of dimensions, 0 to remove the `dim` and `dimnames` attributes (i.e. to create a vector).
`old`	list containing a list with (possibly) elements `dim`, `dimnames`, and `names`. The nth last element of this list is used.
`n`	how many makeNdim steps to go back?
`...`	ignored
`usedim`	use only the specified dimensions
`fromend`	if `TRUE`, numeric `usedim` are counted from the end, see details.
`drop`	should 1d arrays drop to vectors?

Note that missing attributes as well as old.dim = NULL produce a (dimensionless) vector. This is also the case if a lost the old.* attributes during computations like as.numeric, c, etc..

fromend together with numeric usedim specifies dimensions counting from the end. E.g. fromend = TRUE and usedim = 1 : 3 for an array to be restored to 10d means restoring dimensions 8 : 10. fromend = TRUE and usedim = -(1 : 3) restores dimensions 1 to 7.

N-dimensional array

an array

Claudia Beleites

v <- arrayhelpers:::v
v
makeNd (v, 1)
dim (makeNd (v, 1))
dim (makeNd (v, 3))

m <- arrayhelpers:::m
m
makeNd (m, 1)
dim (makeNd (m, 1))
makeNd (m, 0) 
dim (makeNd (m, 0))
makeNd (m, 3)

a <- arrayhelpers:::a
a
dim (makeNd (a, 1))
dim (makeNd (a, 0))
makeNd (a,  2)          
makeNd (a, -2)
makeNd (a, -4)
makeNd (a, 3);


a <- array (1 : 24, 4 : 3)
a
restoredim (makeNd (a, 0))

x <- makeNd (a, 0)
attr (x, "old")