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instance method

Set#classify

[X] () { (A) -> X } -> ::Hash[X, self]

classify {|element| ... } → hash

classify → enumerator

static VALUE
set_i_classify(VALUE set)
{
    RETURN_SIZED_ENUMERATOR(set, 0, 0, set_enum_size);
    VALUE args[3];
    args[0] = rb_hash_new();
    args[1] = rb_obj_class(set);
    args[2] = RBOOL(RSET_COMPARE_BY_IDENTITY(set));
    set_iter(set, set_classify_i, (st_data_t)args);
    return args[0];
}

With a block given, calls the block with each element of self; returns a hash whose keys are the block’s return values. The value for each key is a set containing the elements for which the block returned that key.

This example classifies elements by their classes:

Example

set = Set[*(5..7), *%w[foo bar]] # => Set[5, 6, 7, "foo", "bar"]
set.classify {|element| element.class }
# => {Integer => Set[5, 6, 7], String => Set["foo", "bar"]}

With no block given, returns an Enumerator.

Related: see Methods for Converting.

See also #add? #clear #add #collect! also in 4.0 · 3.4 · 3.3 · 3.2 · 3.1 · 3.0

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