Misha Moroshko - 1 year ago 95

Ruby Question

What is the easiest way to convert

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

to

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

Answer

If you're using ruby 1.8.7 or 1.9, you can use the fact that iterator methods like `each_with_index`

, when called without a block, return an `Enumerator`

object, which you can call `Enumerable`

methods like `map`

on. So you can do:

```
arr.each_with_index.map { |x,i| [x, i+2] }
```

In 1.8.6 you can do:

```
require 'enumerator'
arr.enum_for(:each_with_index).map { |x,i| [x, i+2] }
```