twExtractFromLastDims: twExtractFromLastDims

In twMisc: Utility functions of tw

Description

Extract slices i from array Aext keeping the all first dimensions.

Usage

twExtractFromLastDims(Aext, i, dPrev = c(1))

Arguments

Aext	array to extract from
i	indices in matrix of last dimensions
dPrev	dimensions in front to keep, defaults to rows

Author(s)

Thomas Wutzler

See Also

twExtractDim, twMisc

Examples

(A <- matrix(1:6, ncol=2))
(Aext <- abind::abind( lapply(1:4, function(i){(i)/10+A}), along=0 ))
# Note that the second and third dimension of Aext correspond to A 

# Now we whish to extract from Aext based on 
# a criterion for the second and third dimension 
(B <- diag(3)[,1:2])
i <- which(B != 0)
(A[i])
# how to index Aext to obtain those indices?
resExp <- matrix(0,nrow=nrow(Aext),ncol=length(i) )
for( ii in seq(along.with=i) )
    resExp[,ii] <- Aext[,(i[ii]-1) %% 3+1,(i[ii]-1) %/% 3+1]
(res <- twExtractFromLastDims(Aext,i))
identical( resExp, structure(res, dimnames=NULL) )

twMisc documentation built on May 2, 2019, 6:11 p.m.