method

flatten

v1_8_7_330 - Show latest stable - Class: Array

flatten(...)

public

Returns a new array that is a one-dimensional flattening of this array (recursively). That is, for every element that is an array, extract its elements into the new array. If the optional level argument determines the level of recursion to flatten.

s = [ 1, 2, 3 ]           #=> [1, 2, 3]
t = [ 4, 5, 6, [7, 8] ]   #=> [4, 5, 6, [7, 8]]
a = [ s, t, 9, 10 ]       #=> [[1, 2, 3], [4, 5, 6, [7, 8]], 9, 10]
a.flatten                 #=> [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
a = [ 1, 2, [3, [4, 5] ] ]
a.flatten(1)              #=> [1, 2, 3, [4, 5]]

/*
 *  call-seq:
 *     array.flatten -> an_array
 *     array.flatten(level) -> an_array
 *  
 *  Returns a new array that is a one-dimensional flattening of this
 *  array (recursively). That is, for every element that is an array,
 *  extract its elements into the new array.  If the optional
 *  <i>level</i> argument determines the level of recursion to flatten.
 *     
 *     s = [ 1, 2, 3 ]           #=> [1, 2, 3]
 *     t = [ 4, 5, 6, [7, 8] ]   #=> [4, 5, 6, [7, 8]]
 *     a = [ s, t, 9, 10 ]       #=> [[1, 2, 3], [4, 5, 6, [7, 8]], 9, 10]
 *     a.flatten                 #=> [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
 *     a = [ 1, 2, [3, [4, 5] ] ]
 *     a.flatten(1)              #=> [1, 2, 3, [4, 5]]
 */

static VALUE
rb_ary_flatten(argc, argv, ary)
    int argc;
    VALUE *argv;
    VALUE ary;
{
    int mod = 0, level = -1;
    VALUE result, lv;

    rb_scan_args(argc, argv, "01", &lv);
    if (!NIL_P(lv)) level = NUM2INT(lv);
    if (level == 0) return ary;

    result = flatten(ary, level, &mod);
    if (OBJ_TAINTED(ary)) OBJ_TAINT(result);

    return result;
}

1Note

Make your custom enumerable "flattenable"

stevo · May 5, 2020

Just alias +to_a+ to +to_ary+

class A
include Enumerable

def each
  yield "a"
  yield "b"
end
end


[A.new, A.new].flatten => [#<A:0x00007fbddf1b5d88>, #<A:0x00007fbddf1b5d60>]


class A
def to_ary
  to_a
end
end

[A.new, A.new].flatten => ["a", "b", "a", "b"]

flatten

1Note

Make your custom enumerable "flattenable"

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