Class: SimpleLinearRegression

Inherits:
Object
  • Object
show all
Defined in:
lib/openstudio-standards/btap/costing/btap_costing.rb

Instance Method Summary collapse

Constructor Details

#initialize(xs, ys) ⇒ SimpleLinearRegression

gist.github.com/rweald/3516193#file-full-slr-class-snippet-rb



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# File 'lib/openstudio-standards/btap/costing/btap_costing.rb', line 7

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

Instance Method Details

#mean(values) ⇒ Object 



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# File 'lib/openstudio-standards/btap/costing/btap_costing.rb', line 33

def mean(values)
  total = values.reduce(0) { |sum, x| x + sum }
  return Float(total) / Float(values.length)
end

#slope ⇒ Object 



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# File 'lib/openstudio-standards/btap/costing/btap_costing.rb', line 18

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

  return (numerator / denominator)
end

#y_intercept ⇒ Object 



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# File 'lib/openstudio-standards/btap/costing/btap_costing.rb', line 14

def y_intercept
  return mean(@ys) - (slope * mean(@xs))
end