Array#statistics

Basic descriptive statistics for an Array in ruby. Probably don’t want to run it on arrays that contain non-numeric objects. Haven’t tested it, but it looks mostly right.

class Array
  def statistics
    mean = sum.to_f / length
    i = length / 2 - 1
    median =
      if length % 2 == 0
        (self[i] + self[i + 1]).to_f / 2
      else
        self[i]
      end
    { :n => length, :mean => mean, :median => median, :min => self.min, :max => self.max }
  end
end

Here’s how it works:

>> [1, 2, 3].statistics
=> {:min=>1, :n=>3, :mean=>2.0, :max=>3, :median=>1}
>> [0, 1, 2, 3].statistics
=> {:min=>0, :n=>4, :mean=>1.5, :max=>3, :median=>1.5}

Someone fix it for me if it’s buggy! It could use some robustness checks too. But for now it pleases me to say no more.

About this entry

You’re currently reading “Array#statistics,” an entry on e-huned.com

Published:
02.25.09 / 12pm
Category:
personal