Replace all zeros in array with elements of another array

Question

Say I've got an array like this:

array_1 =  [0, 0, 1, 2, 3, 0]

and another one like this:

array_2 = [4, 5, 6]

How can I create an array like this, such that each 0 in the array_1 is replaced by the first and subsequent elements of the array_2?:

[4, 5, 1, 2, 3, 6]

That is, every time we encounter a 0 in the first array, we'd like to replace it with the result of array_2.shift.

Well, you have half of the answer right there. Use `map` and `shift`, with some conditionals on top. — Sergio Tulentsev, Jul 08 '16 at 20:23

BrunoF · Accepted Answer · 2016-07-09T13:32:05.343

5

This one is shorter but the shift method it will modify array_2 in-place.

array_1.map {|x| x == 0 ? array_2.shift : x}

The following uses an enumerator object with external iteration and will not modify any of the original arrays.

e = array_2.each
array_1.map {|x| x == 0 ? e.next : x}

edited Jul 09 '16 at 13:32

answered Jul 08 '16 at 20:32

BrunoF

2

Even though the OP mentioned array_2.shift, it still should be noted that this mutates `array_2`. – Cary Swoveland Jul 09 '16 at 03:54

score 1 · Answer 2 · answered Jul 08 '16 at 20:31

1

You could do something like this, iterate and shift when you encounter a 0

array_1.each_with_index do |val, i|
  array_1[i] = array_2.shift if val == 0
end

answered Jul 08 '16 at 20:31

user1875195

This is incorrect. The question calls for a new array was to be created (rather than mutating `array_1`). Moreover, even though the OP mentioned `array_2.shift`, it still should be noted that this mutates `array_2` as well. – Cary Swoveland Jul 09 '16 at 03:50

2 Answers2