arrayIndex2vectorIndex: Array: make vector positions from array index

In ff: Memory-Efficient Storage of Large Data on Disk and Fast Access Functions

Array: make vector positions from array index

Description

Make vector positions from a (non-symmetric) array index respecting dim and dimorder

Usage

arrayIndex2vectorIndex(x, dim = NULL, dimorder = NULL, vw = NULL)

Arguments

x	an n by m matrix with n m-dimensional array indices
dim	NULL or dim
dimorder	NULL or dimorder
vw	NULL or integer vector[3] or integer matrix[3,m], see details

Details

The fastest rotating dimension is dim[dimorder[1]], then dim[dimorder[2]], and so forth.
The parameters 'x' and 'dim' may refer to a subarray of a larger array, in this case, the array indices 'x' are interpreted as 'vw[1,] + x' within the larger array 'as.integer(colSums(vw))'.

Value

a vector of indices in seq_len(prod(dim)) (or seq_len(prod(colSums(vw))))

Author(s)

Jens Oehlschlägel

See Also

array2vector, vectorIndex2arrayIndex

Examples

  x <- matrix(1:12, 3, 4)
  x
  arrayIndex2vectorIndex(cbind(as.vector(row(x)), as.vector(col(x)))
  , dim=dim(x))
  arrayIndex2vectorIndex(cbind(as.vector(row(x)), as.vector(col(x)))
  , dim=dim(x), dimorder=2:1)
  matrix(1:30, 5, 6)
  arrayIndex2vectorIndex(cbind(as.vector(row(x)), as.vector(col(x)))
  , vw=rbind(c(0,1), c(3,4), c(2,1)))
  arrayIndex2vectorIndex(cbind(as.vector(row(x)), as.vector(col(x)))
  , vw=rbind(c(0,1), c(3,4), c(2,1)), dimorder=2:1)

ff documentation built on Sept. 30, 2024, 9:38 a.m.