sets {base}

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.



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.



Values

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.



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



is.element() makes for more readable code, and is identical to %in%
v <- c('a','b','c','e')

is.element('b', v)
'b' %in% v
## both return TRUE

is.element('f', v)
'f' %in% v
## both return FALSE

subv <- c('a', 'f')
subv %in% v
## returns a vector TRUE FALSE
is.element(subv, v)
## returns a vector TRUE FALSE