# zip

When no block given, returns a new Array new_array of size self.size whose elements are Arrays.

Each nested array new_array[n] is of size other_arrays.size+1, and contains:

If all other_arrays and self are the same size:

a = [:a0, :a1, :a2, :a3]
b = [:b0, :b1, :b2, :b3]
c = [:c0, :c1, :c2, :c3]
d = a.zip(b, c)
d # => [[:a0, :b0, :c0], [:a1, :b1, :c1], [:a2, :b2, :c2], [:a3, :b3, :c3]]

If any array in other_arrays is smaller than self, fills to self.size with nil:

a = [:a0, :a1, :a2, :a3]
b = [:b0, :b1, :b2]
c = [:c0, :c1]
d = a.zip(b, c)
d # => [[:a0, :b0, :c0], [:a1, :b1, :c1], [:a2, :b2, nil], [:a3, nil, nil]]

If any array in other_arrays is larger than self, its trailing elements are ignored:

a = [:a0, :a1, :a2, :a3]
b = [:b0, :b1, :b2, :b3, :b4]
c = [:c0, :c1, :c2, :c3, :c4, :c5]
d = a.zip(b, c)
d # => [[:a0, :b0, :c0], [:a1, :b1, :c1], [:a2, :b2, :c2], [:a3, :b3, :c3]]

When a block is given, calls the block with each of the sub-arrays (formed as above); returns nil

a = [:a0, :a1, :a2, :a3]
b = [:b0, :b1, :b2, :b3]
c = [:c0, :c1, :c2, :c3]
a.zip(b, c) {|sub_array| p sub_array} # => nil

Output:

[:a0, :b0, :c0]
[:a1, :b1, :c1]
[:a2, :b2, :c2]
[:a3, :b3, :c3]

 
               static VALUE
rb_ary_zip(int argc, VALUE *argv, VALUE ary)
{
    int i, j;
    long len = RARRAY_LEN(ary);
    VALUE result = Qnil;

    for (i=0; i<argc; i++) {
        argv[i] = take_items(argv[i], len);
    }

    if (rb_block_given_p()) {
        int arity = rb_block_arity();

        if (arity > 1) {
            VALUE work, *tmp;

            tmp = ALLOCV_N(VALUE, work, argc+1);

            for (i=0; i<RARRAY_LEN(ary); i++) {
                tmp[0] = RARRAY_AREF(ary, i);
                for (j=0; j<argc; j++) {
                    tmp[j+1] = rb_ary_elt(argv[j], i);
                }
                rb_yield_values2(argc+1, tmp);
            }

            if (work) ALLOCV_END(work);
        }
        else {
            for (i=0; i<RARRAY_LEN(ary); i++) {
                VALUE tmp = rb_ary_new2(argc+1);

                rb_ary_push(tmp, RARRAY_AREF(ary, i));
                for (j=0; j<argc; j++) {
                    rb_ary_push(tmp, rb_ary_elt(argv[j], i));
                }
                rb_yield(tmp);
            }
        }
    }
    else {
        result = rb_ary_new_capa(len);

        for (i=0; i<len; i++) {
            VALUE tmp = rb_ary_new_capa(argc+1);

            rb_ary_push(tmp, RARRAY_AREF(ary, i));
            for (j=0; j<argc; j++) {
                rb_ary_push(tmp, rb_ary_elt(argv[j], i));
            }
            rb_ary_push(result, tmp);
        }
    }

    return result;
}