Module: Bernoulli::Distribution

Included in:
Binomial, Geometric, Hypergeometric, Poisson
Defined in:
lib/bernoulli/distribution.rb,
lib/bernoulli/distribution/poisson.rb,
lib/bernoulli/distribution/binomial.rb,
lib/bernoulli/distribution/geometric.rb,
lib/bernoulli/distribution/hypergeometric.rb

Overview

Top level Module for all the probability distributions Also provides convinience methods and ‘#standard_deviation`, which is calculated the same way independent of the distribution

Defined Under Namespace

Classes: Binomial, Geometric, Hypergeometric, Poisson

Instance Method Summary collapse

Instance Method Details

#[](k) ⇒ Object

A shortcut to the ‘#probability` and `#probability_range` methods

Parameters:

  • k (Integer, Range) 


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# File 'lib/bernoulli/distribution.rb', line 22

def [](k)
  if k.is_a? Integer
    probability(k).to_f
  elsif k.is_a? Range
    probability_range(k).to_f
  else
    raise TypeError, 'Expecting Integer or Range - "[]"'
  end
end

#probability_range(r) ⇒ Object

Calculate the sum of the probabilities across a range

Parameters:

  • r (Range) 


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# File 'lib/bernoulli/distribution.rb', line 15

def probability_range(r)
  r.inject(0) { |s, k| s + probability(k) }
end

#standard_deviation ⇒ Object Also known as: sd

The standard deviation of a random variable is the square root of its variance.



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# File 'lib/bernoulli/distribution.rb', line 34

def standard_deviation
  Math.sqrt(variance)
end