Primitive Cumulative Sum

Cumulative sum of array elements along a single axis. Output position j along axis equals the sum of input positions 1:j.

A boolean input is accumulated with a logical OR, so the result is a running OR rather than a running count. nv_cumsum() counts instead.

Usage

prim_cumsum(x, axis)

Arguments

x

(arrayish)
One input. Can be any data type. An R value materializes at its default data type.

axis

(integer(1))
Axis along which to accumulate. Negative values count from the end, i.e. -1 refers to the last axis.

Value

(arrayish)
Has the input's shape and data type.

Implemented Rules

• stablehlo

• reverse

StableHLO

Lowers to hlo_reduce_window(), specified under reduce_window. The reducer is hlo_add().

See also

nv_cumsum()

Examples

# the accumulation keeps the input's data type
x <- nv_matrix(1:6, nrow = 2)
prim_cumsum(x, axis = 1L)
#> AnvlArray
#>   1  3  5
#>   3  7 11
#> [ CPUi32{2,3} ]