Module: DescriptiveStatistics

Included in:
Enumerable
Defined in:
lib/descriptive_statistics/sum.rb,
lib/descriptive_statistics/mean.rb,
lib/descriptive_statistics/mode.rb,
lib/descriptive_statistics/range.rb,
lib/descriptive_statistics/median.rb,
lib/descriptive_statistics/number.rb,
lib/descriptive_statistics/variance.rb,
lib/descriptive_statistics/percentile.rb,
lib/descriptive_statistics/percentile_rank.rb,
lib/descriptive_statistics/support/convert.rb,
lib/descriptive_statistics/standard_deviation.rb,
lib/descriptive_statistics/descriptive_statistics.rb

Defined Under Namespace

Modules: Support

Instance Method Summary collapse

Instance Method Details

#descriptive_statistics ⇒ Object 



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# File 'lib/descriptive_statistics/descriptive_statistics.rb', line 2

def descriptive_statistics
  return { :number => self.number,
           :sum => self.sum,
           :variance => self.variance,
           :standard_deviation => self.standard_deviation,
           :min => self.min,
           :max => self.max,
           :mean => self.mean,
           :mode => self.mode,
           :median => self.median,
           :range => self.range,
           :q1 => self.percentile(25),
           :q2 => self.percentile(50),
           :q3 => self.percentile(75) }
end

#mean ⇒ Object 



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# File 'lib/descriptive_statistics/mean.rb', line 2

def mean
  values = Support::convert(self)
  return unless values.size > 0

  values.sum / values.number
end

#median ⇒ Object 



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# File 'lib/descriptive_statistics/median.rb', line 2

def median
  values = Support::convert(self)
  return unless values.size > 0

  values.percentile(50)
end

#mode ⇒ Object 



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# File 'lib/descriptive_statistics/mode.rb', line 2

def mode
  values = Support::extract(self)
  return unless values.size > 0

  values
    .group_by { |e| e }
    .values
    .max_by(&:size)
    .first
end

#number ⇒ Object 



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# File 'lib/descriptive_statistics/number.rb', line 2

def number
  values = Support::extract(self)

  values.size.to_f
end

#percentile(p) ⇒ Object 



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# File 'lib/descriptive_statistics/percentile.rb', line 2

def percentile(p)
  values = Support::convert(self)
  return unless values.size > 0

  sorted = values.sort
  return sorted[-1] if p == 100        
  rank = p / 100.0 * (values.number - 1) 
  lrank = rank.floor
  d = rank - lrank
  lower = sorted[lrank]
  upper = sorted[lrank+1]
  lower + (upper - lower) * d
end

#percentile_rank(p) ⇒ Object

percent of cases that are at or below a score



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# File 'lib/descriptive_statistics/percentile_rank.rb', line 3

def percentile_rank(p)
  values = Support::convert(self)
  return unless values.size > 0

  return (((values.sort.rindex{ |x| x <= p } || -1.0) + 1.0)) / values.number * 100.0
end

#range ⇒ Object 



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# File 'lib/descriptive_statistics/range.rb', line 2

def range
  values = Support::convert(self)
  return unless values.size > 0

  values.max - values.min
end

#standard_deviation ⇒ Object 



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# File 'lib/descriptive_statistics/standard_deviation.rb', line 2

def standard_deviation
  values = Support::convert(self)
  return unless values.size > 0

  Math.sqrt(values.variance)
end

#sum ⇒ Object 



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# File 'lib/descriptive_statistics/sum.rb', line 2

def sum 
  values = Support::convert(self)
  return unless values.size > 0

  return values.inject(:+)
end

#variance ⇒ Object 



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# File 'lib/descriptive_statistics/variance.rb', line 2

def variance
  values = Support::convert(self)
  return unless values.size > 0

  mean = values.mean
  values.map{ |sample| (mean - sample) ** 2 }.inject(:+) / values.number
end