rje (version 1.12.1)

patternRepeat: Complex repetitions

Description

Recreate patterns for collapsed arrays

Usage

patternRepeat(x, which, n, careful = TRUE, keep.order = FALSE)
patternRepeat0(which, n, careful = TRUE, keep.order = FALSE)

Value

Both return a vector of length prod(n); patternRepeat() one containing suitably repeated and ordered elements of x, for patternRepeat0() it is always the integers from 1 up to prod(n[which]).

Arguments

x

A vector to be repeated.

which

Which indices of the implicit array are given in x.

n

Dimensions of implicit array.

careful

logical indicating whether to check vailidty of arguments, but therefore slow things down.

keep.order

logical indicating whether to respect the ordering of the entries in the vector which, in which case data are permuted before replication. In other words, does x change fastest in which[1], or in the minimal entry for which?

Functions

• patternRepeat0: Stripped down version that just gives indices

Author

Robin Evans

Details

These functions allow for the construction of complex repeating patterns corresponding to those obtained by unwrapping arrays. Consider an array with dimensions n; then for each value of the dimensions in which, this function returns a vector which places the corresponding entry of x into every place which would match this pattern when the full array is unwrapped.

For example, if a full 4-way array has dimensions 2*2*2*2 and we consider the margin of variables 2 and 4, then the function returns the pattern c(1,1,2,2,1,1,2,2,3,3,4,4,3,3,4,4). The entries 1,2,3,4 correspond to the patterns (0,0), (1,0), (0,1) and (1,1) for the 2nd and 4th indices.

In patternRepeat() the argument x is repeated according to the pattern, while patternRepeat0() just returns the indexing pattern. So patternRepeat(x,which,n) is effectively equivalent to x[patternRepeat0(which,n)].

The length of x must be equal to prod(n[which]).

See Also

rep

Examples

patternRepeat(1:4, c(1,2), c(2,2,2))
c(array(1:4, c(2,2,2)))

patternRepeat0(c(1,3), c(2,2,2))
patternRepeat0(c(2,3), c(2,2,2))

patternRepeat0(c(3,1), c(2,2,2))
patternRepeat0(c(3,1), c(2,2,2), keep.order=TRUE)

patternRepeat(letters[1:4], c(1,3), c(2,2,2))