From: "Bartosz Dziewoński" <matma.rex@...>
Date: 2011-09-10T23:43:59+09:00
Subject: Re: Not 2 maps

A marginally faster solution would be

arr.each{|y| y.map!{|z| z.to_i}}

This doesn't create new objects, instead modifying arrays in place.
It's about 15% faster for me.

Benchmark: https://gist.github.com/1208377

-- Matma Rex