array-slice: Array slices
In gRbase: A Package for Graphical Modelling in R

Description Usage Arguments Author(s) See Also Examples

Functions for extracting slices of arrays

ar_slice(tab, slice = NULL, margin = names(slice), drop = TRUE,
  as.array = FALSE)

ar_slice_prim(tab, slice, drop = TRUE)

ar_slice_mult(tab, slice, val = 1, comp = 0)

ar_slice_entries(tab, slice, complement = FALSE)

`tab`	An array with named dimnames.
`slice`	A list defining the slice.
`margin`	Names of variables in slice.
`drop`	If TRUE then dimensions with only one level will be dropped from the output.
`as.array`	If the resulting array is one-dimensional the result will by default be a vector with no dim attribute unless as.array is TRUE.
`val`	The values that entries in the slice will be multiplied with.
`comp`	The values that entries NOT in the slice will be multiplied with.
`complement`	If TRUE the complement of the entries are returned.

S<c3><b8>ren H<c3><b8>jsgaard, sorenh@math.aau.dk

ar_perm, ar_marg, ar_mult, ar_div, ar_add, ar_subt, ar_sum, ar_prod

x = HairEyeColor
s = list(Hair=c("Black","Brown"), Eye=c("Brown", "Blue"))

## arslice
s1 = ar_slice(x, slice=s)
s1

## ar_slice_entries
ar_slice_entries(x, slice=s)
ar_slice_entries(x, slice=s, complement=TRUE)

## ar_slice_mult
s2 = ar_slice_mult(x, slice=s)
s2

## arslice_prim does the same as arslice - faster, but the function is less
# flexible
sp = list(c(1,2), c(1,2), TRUE)
ar_slice_prim(x, slice=sp)
ar_slice(x, slice=s)
if ( require(microbenchmark) ){
  microbenchmark(ar_slice_prim(x, slice=sp), ar_slice(x, slice=s))
}