Ruby Array to Histogram: How to group numbers by range?
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I'm trying to group an array of integers into an hash based on where the individual values fall in a range. Basically I want to convert an array to a fixed-width histogram.

**Example:**

    values = [1,3,4,4,4,4,4,10,12,15,18]
    bin_width = 3

I need to group the array values into a range-based historgram by where they fall into a 3-unit wide bucket like so: 

    {'0..2'=>[1,3],'3..5'=>[4,4,4,4,4],'6..8'=>[],'9..11'=>[10]....


Is there a simple one line solution ( maybe something like `values.group_by{|x| #range calc}`) that would work here?

  [1]: http://en.wikipedia.org/wiki/Histogram#Number_of_bins_and_width