Get or set elements of an array by index

rray_extract() is the counterpart to rray_yank(). It extracts elements from an array by index. It always drops dimensions (unlike rray_subset()), and a 1D object is always returned.

rray_extract(x, ...) <- value

rray_extract_assign(x, ..., value)

rray_extract(x, ...)

Arguments

x	A vector, matrix, array, or rray.
...	A specification of indices to extract. Integer-ish indices extract specific elements of dimensions. Logical indices must be length 1, or the length of the dimension you are subsetting over. Character indices are only allowed if x has names for the corresponding dimension. NULL is treated as 0.
value	The value to assign to the location specified by .... Before assignment, value is cast to the type and dimension of x after extracting elements with ....

Value

A 1D vector of elements extracted from x.

Details

Like [[, rray_extract() will never keep dimension names.

rray_extract() works with base R objects as well.

rray_extract() is similar to the traditional behavior of x[[i, j, ...]], but allows each subscript to have length >1.

See also

Other rray subsetters: rray_slice<-, rray_subset<-, rray_yank<-

Examples

x <- rray(1:16, c(2, 4, 2), dim_names = list(c("r1", "r2"), NULL, NULL))

# Extract the first row and flatten it
rray_extract(x, 1)
#> [1]  1  3  5  7  9 11 13 15

# Extract the first row and first two columns
rray_extract(x, 1, 1:2)
#> [1]  1  3  9 11

# You can assign directly to these elements
rray_extract(x, 1, 1:2) <- NA
x
#> <rray<int>[,4,2][2]>
#> , , 1
#> 
#>    [,1] [,2] [,3] [,4]
#> r1   NA   NA    5    7
#> r2    2    4    6    8
#> 
#> , , 2
#> 
#>    [,1] [,2] [,3] [,4]
#> r1   NA   NA   13   15
#> r2   10   12   14   16
#>