Stack arrays along a new axis

rray_stack() joins arrays along a new axis inserted at .axis. All preexisting axes are broadcast to their common dimension.

The new axis has a dimension equal to the number of arrays you are stacking.

Usage

rray_stack(..., .axis)

Arguments

...

Arrays to stack.

.axis

A single integer representing the axis in the result to stack along. Must be between 1 and one greater than the maximum dimensionality of the input arrays. For example, you can stack 2D matrices along axis 3, but not axis 4.

Value

An array with the following dimensions:

• Along .axis, the number of inputs.

• Along all other axes, the common dimensions of the inputs taken via broadcasting.

Details

Names of ... become the names of the new axis. Existing axis names are otherwise carried over.

See also

rray_unstack(), rray_combine()

Examples

x <- array(1:12, c(3, 4))
y <- array(13:24, c(3, 4))

# (3, 4) -> (2, 3, 4)
rray_dimensions(rray_stack(x, y, .axis = 1))
#> [1] 2 3 4

# (3, 4) -> (3, 4, 2)
rray_stack(x, y, .axis = 3)
#> , , 1
#> 
#>      [,1] [,2] [,3] [,4]
#> [1,]    1    4    7   10
#> [2,]    2    5    8   11
#> [3,]    3    6    9   12
#> 
#> , , 2
#> 
#>      [,1] [,2] [,3] [,4]
#> [1,]   13   16   19   22
#> [2,]   14   17   20   23
#> [3,]   15   18   21   24
#> 

# Existing axes are broadcast
# (3, 1) and (3, 4) -> (2, 3, 4)
a <- array(1:3, c(3, 1))
b <- array(1:12, c(3, 4))
rray_dimensions(rray_stack(a, b, .axis = 1))
#> [1] 2 3 4

# Names of `...` name the new axis
rray_stack(first = 1:2, second = 3:4, .axis = 2)
#>      first second
#> [1,]     1      3
#> [2,]     2      4