Method: Array#to_h

Defined in:

array.c

#to_h ⇒ Object #to_h {|element| ... } ⇒ Object

Returns a new hash formed from self.

With no block given, each element of self must be a 2-element sub-array; forms each sub-array into a key-value pair in the new hash:

a = [['foo', 'zero'], ['bar', 'one'], ['baz', 'two']]
a.to_h # => {"foo"=>"zero", "bar"=>"one", "baz"=>"two"}
[].to_h # => {}

With a block given, the block must return a 2-element array; calls the block with each element of self; forms each returned array into a key-value pair in the returned hash:

a = ['foo', :bar, 1, [2, 3], {baz: 4}]
a.to_h {|element| [element, element.class] }
# => {"foo"=>String, :bar=>Symbol, 1=>Integer, [2, 3]=>Array, {:baz=>4}=>Hash}

Related: see Methods for Converting.

Overloads:

• #to_h {|element| ... } ⇒ Object

  Yields:

  • (element)

# File 'array.c', line 3065

static VALUE
rb_ary_to_h(VALUE ary)
{
    long i;
    VALUE hash = rb_hash_new_with_size(RARRAY_LEN(ary));
    int block_given = rb_block_given_p();

    for (i=0; i<RARRAY_LEN(ary); i++) {
        const VALUE e = rb_ary_elt(ary, i);
        const VALUE elt = block_given ? rb_yield_force_blockarg(e) : e;
        const VALUE key_value_pair = rb_check_array_type(elt);
        if (NIL_P(key_value_pair)) {
            rb_raise(rb_eTypeError, "wrong element type %"PRIsVALUE" at %ld (expected array)",
                     rb_obj_class(elt), i);
        }
        if (RARRAY_LEN(key_value_pair) != 2) {
            rb_raise(rb_eArgError, "wrong array length at %ld (expected 2, was %ld)",
                i, RARRAY_LEN(key_value_pair));
        }
        rb_hash_aset(hash, RARRAY_AREF(key_value_pair, 0), RARRAY_AREF(key_value_pair, 1));
    }
    return hash;
}