Drop Array Dimension(s) of Length One

Usage

dropDim(x, dimension = which(dim(x) == 1))

Arguments

x: an array
dimension: number(s) of dimension(s) of length one to be removed

Value

array with dimensions of which the numbers are given in

dimension removed

Examples

# Define an array of two matrices
A <- array(
1:8, dim = c(2, 2, 2), dimnames = list(
    paste0("x", 1:2), paste0("y", 1:2), paste0("z", 1:2))
)

# The aim is to select the first column of the first matrix with
# the matrix structure being kept. This cannot be done with the
# standard "[" operator. It has indeed a "drop" argument but this
# acts on all dimensions:

# By default, drop is TRUE. The result is a named vector
A[, 1, 1]
#> x1 x2 
#>  1  2 

# With drop = FALSE we get a 3D-array again and not a matrix
A[, 1, 1, drop = FALSE]
#> , , z1
#> 
#>    y1
#> x1  1
#> x2  2
#> 

# Use dropDim to remove the third dimension of an array that
# has already one dimension of length one
dropDim(A[, 1, 1, drop = FALSE], dimension = 3)
#>    y1
#> x1  1
#> x2  2