Method: Array#union

Defined in:
array.c

#union(*other_arrays) ⇒ Object

Returns a new array that is the union of the elements of self and all given arrays other_arrays; items are compared using eql?:

[0, 1, 2, 3].union([4, 5], [6, 7]) # => [0, 1, 2, 3, 4, 5, 6, 7]

Removes duplicates (preserving the first found):

[0, 1, 1].union([2, 1], [3, 1]) # => [0, 1, 2, 3]

Preserves order (preserving the position of the first found):

[3, 2, 1, 0].union([5, 3], [4, 2]) # => [3, 2, 1, 0, 5, 4]

With no arguments given, returns a copy of self.

Related: see Methods for Combining.



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# File 'array.c', line 5802

static VALUE
rb_ary_union_multi(int argc, VALUE *argv, VALUE ary)
{
    int i;
    long sum;
    VALUE hash;

    sum = RARRAY_LEN(ary);
    for (i = 0; i < argc; i++) {
        argv[i] = to_ary(argv[i]);
        sum += RARRAY_LEN(argv[i]);
    }

    if (sum <= SMALL_ARRAY_LEN) {
        VALUE ary_union = rb_ary_new();

        rb_ary_union(ary_union, ary);
        for (i = 0; i < argc; i++) rb_ary_union(ary_union, argv[i]);

        return ary_union;
    }

    hash = ary_make_hash(ary);
    for (i = 0; i < argc; i++) rb_ary_union_hash(hash, argv[i]);

    return rb_hash_values(hash);
}