Contents

require File.expand_path(File.dirname(__FILE__) + '/spec_helper')

describe "LeastSquares" do
  before(:each) do
    @xs = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
    @ys = [9, 1, 0, 5, 4, 7, 7, 0, 9, 3]
  end

  describe '#mean' do
    specify 'returns the mean (average) of an array of numbers' do
      Math.mean(@xs).should == 5.5
      Math.mean(@ys).should == 4.5
    end
  end

  describe '#stdev' do
    specify 'returns the standard deviation of an array of numbers' do
      Math.stdev(@xs).should be_close(3.0277, 0.0001)
      Math.stdev(@ys).should be_close(3.4721, 0.0001)
    end
  end

  describe '#pearson' do
    specify 'returns the Pearson Correlation Coefficient of two arrays of numbers' do
      Math.pearson(@xs,@ys).should be_close(0.0581, 0.0001)
    end
  end

  describe '#least_squares' do
    specify 'returns the Least Squares Regression Line of two arrays of numbers as a Proc' do
      Math.least_squares(@xs,@ys).should be_a(Proc)
    end

    specify 'return the Least Squares Regression Line of two arrays of numbers' do
      rs = [4.2, 4.2667, 4.3333, 4.4, 4.4667, 4.5333, 4.6, 4.6667, 4.7333, 4.8]
      ls = Math.least_squares(@xs,@ys)
      (1..10).map{|i| ls.call(i)}.each_with_index do |x,i|
        x.should be_close(rs[i], 0.0001)
      end
    end
  end
end

Version data entries

2 entries across 2 versions & 1 rubygems

Version	Path
least_squares-0.1.1	spec/least_squares_spec.rb
least_squares-0.1.0	spec/least_squares_spec.rb