Find common dimensions

Source: R/dim.R

  • rray_dim() finds the dimension of a single object.

  • rray_dim_common() finds the common dimensions of a set of objects.

rray_dim(x)

rray_dim_common(...)

Arguments

x

An object.
...

Objects to find common dimensions for.

Value

An integer vector containing the common dimensions.

Details

rray_dim_common() first finds the common dimensionality, makes any implicit dimensions explicit, then recycles the size of each dimension to a common size.

As an example, the common dimensions of (4, 5) and (4, 1, 2) are:

(4, 5, 1) <- implicit 1 is made to be explicit, then recycled to 2
(4, 1, 2) <- the 1 in the second dimension here is recycled to 5
---------
(4, 5, 2) <- resulting common dim

The resulting dimensions from rray_dim_common() are the dimensions that are used in broadcasted operations.

See also

rray_dim_n()

Examples

x_1_by_4 <- rray(c(1, 2, 3, 4), c(1, 4))
x_5_by_1 <- rray(1:5, c(5, 1))

rray_dim(x_1_by_4)
#> [1] 1 4

# recycle rows: 1 VS 5 = 5
# recycle cols: 4 VS 1 = 4
rray_dim_common(x_1_by_4, x_5_by_1)
#> [1] 5 4

x_5_by_1_by_3 <- rray(1, c(5, 1, 3))

# recycle rows:    5 VS 1 = 5
# recycle cols:    4 VS 1 = 4
# recycle 3rd dim: 1 VS 3 = 3
# (here, 3rd dim of 1 for the matrix is implicit)
rray_dim_common(x_1_by_4, x_5_by_1_by_3)
#> [1] 5 4 3

# The dimensions of NULL are 0
rray_dim(NULL)
#> [1] 0