graph.rb

#!/bin/env ruby -wdK
# Given an array, print it as a bar graph
# Use FOR SPEED!!!
class VerticalAsciiGraph
  WIDTH = 72
  STEPS = WIDTH/6

  def self.draw(sample)
    new(sample).draw
  end

  def initialize(array)
    @values = array
    @height = array.size
    @max    = array.max
  end
  private :initialize

  # initialize display with blanks
  def graph
    @values.map do |value|
      line = value * WIDTH / @max
      str =  "%f" % value + ' ' + '#' * (line - 12)
      color = @values.outlier?(value) ? :red : :none
      str = CLI.colorize(str, color)
      str
    end
  end

  def markers
    (1..STEPS).map{|i| i * @max.ceil / STEPS }.map{|i| i.to_s.rjust(6, '-')}.join
  end

  def draw
    puts graph
    puts markers
    puts
    printf "The mean is %f\n", @values.without_outliers.average
    printf "The standard deviation is %f\n", @values.without_outliers.standard_deviation
    puts "Bars in #{CLI.colorize("red", :red)} represent outliers."
  end
end

module CLI
  class << self
    COLORS = {
      :none     => "\033[0m",
      :red      => "\033[31m",
      :green_bg => "\033[42m",
      :red_bg   => "\033[41m",
      :white_bg => "\033[47m"
    }

    COLORS.each_key do|color|
      define_method color do |text|
        colorize(text, color)
      end
    end

    def colorize(text, color)
      "#{COLORS[color]}#{text}\033[0m"
    end
  end
end

module Enumerable
  def sum
    self.inject(0) { |acc, i| acc + i }
  end

  def average
    self.sum / self.length.to_f
  end

  # This is a stupid way to calculate outliers but it is vaguely effective
  # some of the time
  def outlier?(item)
    item > self.max * 0.9 || item < self.max * 0.1
  end

  def without_outliers
    reject{|item| self.outlier?(item) }
  end

  def sample_variance
    avg = self.average
    sum = self.inject(0) { |acc, i| acc + (i - avg) ** 2 }
    (1 / self.length.to_f * sum)
  end

  def standard_deviation
    Math.sqrt(self.sample_variance)
  end
end

if __FILE__ == $PROGRAM_NAME
  sample = [545.993804931641, 560.154914855957, 660.984992980957, 594.608068466187, 563.859939575195, 669.82889175415, 577.944040298462, 688.918828964233, 990.634918212891, 582.823038101196, 676.376104354858, 584.000825881958, 587.714910507202, 662.652969360352, 575.167179107666, 696.619987487793, 563.127040863037, 571.943044662476, 685.527801513672, 590.106010437012]
  VerticalAsciiGraph.draw sample
end