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Generalized array addition

aplus.Rd

Given two arrays a and b with length(dim(a))==length(dim(b)), return a matrix with dimensions pmax(dim(a),dim(b)) where “overlap” elements are a+b, and the other elements are either 0, a, or b according to location. See details section.

Usage

aplus(...)

Arguments

...

numeric or complex arrays

Details

The function takes any number of arguments (the binary operation is associative).

The operation of aplus() is understandable by examining the following pseudocode:

  • outa <- array(0,pmax(a,b))

  • outb <- array(0,pmax(a,b))

  • outa[1:dim(a)] <- a

  • outb[1:dim(a)] <- b

  • return(outa+outb)

See how outa and outb are the correct size and the appropriate elements of each are populated with a and b respectively. Then the sum is returned.

Author

Robin K. S. Hankin

See also

apad

Examples


aplus(rbind(1:9),cbind(1:9))
#>       [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9]
#>  [1,]    2    2    3    4    5    6    7    8    9
#>  [2,]    2    0    0    0    0    0    0    0    0
#>  [3,]    3    0    0    0    0    0    0    0    0
#>  [4,]    4    0    0    0    0    0    0    0    0
#>  [5,]    5    0    0    0    0    0    0    0    0
#>  [6,]    6    0    0    0    0    0    0    0    0
#>  [7,]    7    0    0    0    0    0    0    0    0
#>  [8,]    8    0    0    0    0    0    0    0    0
#>  [9,]    9    0    0    0    0    0    0    0    0

a <- matrix(1:8,2,4)
b <- matrix(1:10,5,2)
aplus(a*100,b,b)
#>      [,1] [,2] [,3] [,4]
#> [1,]  102  312  500  700
#> [2,]  204  414  600  800
#> [3,]    6   16    0    0
#> [4,]    8   18    0    0
#> [5,]   10   20    0    0