How to map with index in Ruby?

Question

What is the easiest way to convert

[x1, x2, x3, ... , xN]

to

[[x1, 2], [x2, 3], [x3, 4], ... , [xN, N+1]]

Answer 1

In ruby 1.9.3 there is a chainable method called with_index which can be chained to map.

For example:

array.map.with_index { |item, index| ... }