16 lines
304 B
Ruby
16 lines
304 B
Ruby
|
# TODO: Avoid monkey-patching.
|
||
|
|
module Enumerable
|
||
|
|
def mean
|
||
|
|
self.reduce(:+) / self.length.to_f
|
||
|
|
end
|
||
|
|
|
||
|
|
def variance
|
||
|
|
mean = self.mean
|
||
|
|
self.reduce(0) { |memo, value| memo + ((value - mean) ** 2) } / (self.length - 1).to_f
|
||
|
|
end
|
||
|
|
|
||
|
|
def standard_deviation
|
||
|
|
Math.sqrt(self.variance)
|
||
|
|
end
|
||
|
|
end
|