base (version 3.3.3)

sets: 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

x, y, el, set

vectors (of the same mode) containing a sequence of items (conceptually) with no duplicated values.

Value

A vector of the same mode as x or y for setdiff and intersect, respectively, and of a common mode for union. A logical scalar for setequal and a logical of the same length as x for is.element.

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.

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