Set Operations

Description

Performs set union, intersection, (asymmetric!) difference, equality and membership on two vectors.

Usage

union(x, y)
intersect(x, y)
setdiff(x, y)
setequal(x, y)

is.element(el, set)

Arguments

Details

Each of union, intersect, setdiff and setequal will discard any duplicated values in the arguments, and they apply as.vector to their arguments (and so in particular coerce factors to character vectors).

is.element(x, y) is identical to x %in% y.

Value

For union, a vector of a common mode.

For intersect, a vector of a common mode, or NULL if x or y is NULL.

For setdiff, a vector of the same mode as x.

A logical scalar for setequal and a logical of the same length as x for is.element.

See Also

%in%

‘plotmath’ for the use of union and intersect in plot annotation.

Examples

(x <- c(sort(sample(1:20, 9)), NA))
(y <- c(sort(sample(3:23, 7)), NA))
union(x, y)
intersect(x, y)
setdiff(x, y)
setdiff(y, x)
setequal(x, y)

## True for all possible x & y :
setequal( union(x, y),
          c(setdiff(x, y), intersect(x, y), setdiff(y, x)))

is.element(x, y) # length 10
is.element(y, x) # length  8