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Determine whether one vector is a subset of another

Source: R/is_subset.R
is_subset.Rd

Check if all elements of x are also contained in y. This is equivalent to testing whether setdiff(x, y) is empty.

Usage

is_subset(x, y)

Arguments

x

The first vector.

y

The second vector.

Value

A logical scalar. Returns TRUE if x is a subset of y, i.e. all elements of x are also elements of y. Returns FALSE otherwise.

Details

  • If x is empty, the result is always TRUE (the empty set is a subset of any set).

  • If y is empty and x is not, the result is FALSE.

  • Duplicates in x are ignored; only set membership is tested.

  • NA values are treated as ordinary elements. In particular, NA in x is considered a subset element only if NA is also present in y.

See also

generics::setdiff(), generics::intersect(), generics::union()

Author

Michal Burda

Examples

is_subset(1:3, 1:5)               # TRUE
#> [1] TRUE
is_subset(c(2, 5), 1:4)           # FALSE
#> [1] FALSE
is_subset(numeric(0), 1:5)        # TRUE
#> [1] TRUE
is_subset(1:3, numeric(0))        # FALSE
#> [1] FALSE
is_subset(c(1, NA), c(1, 2, NA))  # TRUE
#> [1] TRUE
is_subset(c(NA), 1:5)             # FALSE
#> [1] FALSE