Question

For instance, I have a

arr = [1,2,3,4]

If I call arr.each, I will access:

1
2
3
4

But I want

1 2
2 3
3 4

Is it possible with built-in function? If not, what’s the best practice?

Another question: if I want 1 2 and 3 4?

Answer 1

You probably want to look at each_cons for your first case:

(1..10).each_cons(3) {|a| p a}
# outputs below
[1, 2, 3]
[2, 3, 4]
[3, 4, 5]
[4, 5, 6]
[5, 6, 7]
[6, 7, 8]
[7, 8, 9]
[8, 9, 10]

For your second case (wanting sets of elements) you would use each_slice:

(1..10).each_slice(3) {|a| p a}
# outputs below
[1, 2, 3]
[4, 5, 6]
[7, 8, 9]
[10]

Either of these methods accepts a single integer specifying the size of the set, so you would specify 2 instead of 3 (examples are straight from the documentation).