class Spina::Shop::SimpleLinearRegression
Public Class Methods
new(xs, ys)
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# File lib/spina/shop/simple_linear_regression.rb, line 4 def initialize(xs, ys) @xs, @ys = xs, ys if @xs.length != @ys.length raise "Unbalanced data. xs need to be same length as ys" end end
Public Instance Methods
mean(values)
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# File lib/spina/shop/simple_linear_regression.rb, line 30 def mean(values) total = values.reduce(0) { |sum, x| x + sum } Float(total) / Float(values.length) end
slope()
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# File lib/spina/shop/simple_linear_regression.rb, line 15 def slope x_mean = mean(@xs) y_mean = mean(@ys) numerator = (0...@xs.length).reduce(0) do |sum, i| sum + ((@xs[i] - x_mean) * (@ys[i] - y_mean)) end denominator = @xs.reduce(0) do |sum, x| sum + ((x - x_mean) ** 2) end (numerator / denominator) end
y_intercept()
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# File lib/spina/shop/simple_linear_regression.rb, line 11 def y_intercept mean(@ys) - (slope * mean(@xs)) end