outer

R Base 3.6.2

The outer product of the arrays X and Y is the array A with dimension c(dim(X), dim(Y)) where element A[c(arrayindex.x, arrayindex.y)] = FUN(X[arrayindex.x], Y[arrayindex.y], …).

Syntax

outer(X, Y, FUN = "*", &#8230;)
X %o% Y

Arguments

Parameter	Description
`X, Y`	First and second arguments for function FUN. Typically a vector or array.
`FUN`	a function to use on the outer products, found via match.fun (except for the special case "*").
`…`	optional arguments to be passed to FUN.

Details

X and Y must be suitable arguments for FUN. Each will be extended by rep to length the products of the lengths of X and Y before FUN is called. FUN is called with these two extended vectors as arguments (plus any arguments in …). It must be a vectorized function (or the name of one) expecting at least two arguments and returning a value with the same length as the first (and the second). Where they exist, the [dim]names of X and Y will be copied to the answer, and a dimension assigned which is the concatenation of the dimensions of X and Y (or lengths if dimensions do not exist). FUN = "*" is handled as a special case via as.vector(X) %*% t(as.vector(Y)), and is intended only for numeric vectors and arrays. %o% is binary operator providing a wrapper for outer(x, y, "*").

Examples

Example

# NOT RUN {
x <- 1:9; names(x) <- x
# Multiplication & Power Tables
x %o% x
y <- 2:8; names(y) <- paste(y,":", sep = "")
outer(y, x, "^")

outer(month.abb, 1999:2003, FUN = "paste")

## three way multiplication table:
x %o% x %o% y[1:3]
# }

outer

Syntax

Arguments

Details

Examples

See Also