Calculate the sum along an axis

rray_sum() computes the sum along a given axis or axes. The dimensionality of x is retained in the result.

rray_sum(x, axes = NULL)

Arguments

x	A vector, matrix, or array to reduce.
axes	An integer vector specifying the axes to reduce over. 1 reduces the number of rows to 1, performing the reduction along the way. 2 does the same, but with the columns, and so on for higher dimensions. The default reduces along all axes.

Value

The result of the reduction as a double with the same shape as x, except along axes, which have been reduced to size 1.

See also

Other reducers: rray_max, rray_mean, rray_min, rray_prod

Examples

x <- rray(1:10, c(5, 2))

# Reduce the number of rows to 1,
# summing along the way
rray_sum(x, 1)
#> <rray<dbl>[,2][1]>
#>      [,1] [,2]
#> [1,]   15   40

# Reduce the number of columns to 1,
# summing along the way
rray_sum(x, 2)
#> <rray<dbl>[,1][5]>
#>      [,1]
#> [1,]    7
#> [2,]    9
#> [3,]   11
#> [4,]   13
#> [5,]   15

# Reduce along all axes, but keep dimensions
rray_sum(x)
#> <rray<dbl>[,1][1]>
#>      [,1]
#> [1,]   55

# Column-wise proportions
x / rray_sum(x, 1)
#> <rray<dbl>[,2][5]>
#>            [,1]  [,2]
#> [1,] 0.06666667 0.150
#> [2,] 0.13333333 0.175
#> [3,] 0.20000000 0.200
#> [4,] 0.26666667 0.225
#> [5,] 0.33333333 0.250

# Row-wise proportions
x / rray_sum(x, 2)
#> <rray<dbl>[,2][5]>
#>           [,1]      [,2]
#> [1,] 0.1428571 0.8571429
#> [2,] 0.2222222 0.7777778
#> [3,] 0.2727273 0.7272727
#> [4,] 0.3076923 0.6923077
#> [5,] 0.3333333 0.6666667

# Reducing over multiple axes
# This reduces over the rows and columns
# of each mini-matrix in the 3rd dimension
y <- rray(1:24, c(2, 3, 4))
rray_sum(y, c(1, 2))
#> <rray<dbl>[,1,4][1]>
#> , , 1
#> 
#>      [,1]
#> [1,]   21
#> 
#> , , 2
#> 
#>      [,1]
#> [1,]   57
#> 
#> , , 3
#> 
#>      [,1]
#> [1,]   93
#> 
#> , , 4
#> 
#>      [,1]
#> [1,]  129
#>