Extracts a subset from an array. You can also use the [ operator.
Supports R-style indexing including scalar indices (which drop axes),
ranges (a:b), and array(c(...)) for selecting multiple elements along a
axis.
Arguments
- x
(
arrayish)
One input. Can be any data type. An R value materializes at its default data type.- ...
Subset specifications, one per axis. Omitted trailing axes select all elements. See
vignette("subsetting")for details.
Value
(arrayish)
Has the input's data type, and the shape the specifications select –
a scalar index drops its axis, a range or an index array keeps it.
See also
nv_subset_assign() for updating subsets, vignette("subsetting")
for a comprehensive guide.
Examples
x <- nv_matrix(1:12, nrow = 3)
x
#> AnvlArray
#> 1 4 7 10
#> 2 5 8 11
#> 3 6 9 12
#> [ CPUi32{3,4} ]
# select row 2
nv_subset(x, 2)
#> AnvlArray
#> 2
#> 5
#> 8
#> 11
#> [ CPUi32{4} ]
x[2, ]
#> AnvlArray
#> 2
#> 5
#> 8
#> 11
#> [ CPUi32{4} ]
# select rows 1 to 2, all columns
nv_subset(x, 1:2)
#> AnvlArray
#> 1 4 7 10
#> 2 5 8 11
#> [ CPUi32{2,4} ]
x[1:2, ]
#> AnvlArray
#> 1 4 7 10
#> 2 5 8 11
#> [ CPUi32{2,4} ]