Class: StatisticalSpread

Inherits:
Struct
  • Object
show all
Defined in:
lib/flash_math/modules/statistics/statistical_spread.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Instance Attribute Details

#values ⇒ Object

Returns the value of attribute values

Returns:

  • (Object) —

    the current value of values



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# File 'lib/flash_math/modules/statistics/statistical_spread.rb', line 1

def values
  @values
end

Instance Method Details

#kurtosis ⇒ Object 



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# File 'lib/flash_math/modules/statistics/statistical_spread.rb', line 103

def kurtosis
  return if values.length == 0
  return 0 if values.length == 1
  StatisticalSpread.new(values).sum_quarted_deviation / ((values.length - 1) * StatisticalSpread.new(values).quarted_standard_deviation.to_f)
end

#max ⇒ Object 



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# File 'lib/flash_math/modules/statistics/statistical_spread.rb', line 46

def max
  return if values.length < 1
  values.sort.last
end

#mean ⇒ Object 



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# File 'lib/flash_math/modules/statistics/statistical_spread.rb', line 11

def mean
  return if values.length < 1
  sum / values.length.to_f
end

#median ⇒ Object 



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# File 'lib/flash_math/modules/statistics/statistical_spread.rb', line 16

def median
  return if values.length < 1
  sorted = values.sort

  if values.length % 2 == 0
    (sorted[(values.length / 2) -1] + sorted[values.length / 2]) / 2.0
  else
    sorted[values.length / 2]
  end
end

#min ⇒ Object 



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# File 'lib/flash_math/modules/statistics/statistical_spread.rb', line 51

def min
  return if values.length < 1
  values.sort.first
end

#mode ⇒ Object 



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# File 'lib/flash_math/modules/statistics/statistical_spread.rb', line 27

def mode
  return if values.length < 1
  frequency_distribution = values.inject(Hash.new(0)) { |hash, value| hash[value] += 1; hash }
  top_2 = frequency_distribution.sort { |a,b| b[1] <=> a[1] } .take(2)
  if top_2.length == 1
    top_2.first.first
  elsif top_2.first.last == top_2.last.last
    nil
  else
    top_2.first.first
  end
end

#percentile_from_value(value) ⇒ Object 



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# File 'lib/flash_math/modules/statistics/statistical_spread.rb', line 56

def percentile_from_value(value)
  return if values.length < 1
  (values.sort.index(value) / values.length.to_f * 100).ceil
end

#population_standard_deviation ⇒ Object 



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# File 'lib/flash_math/modules/statistics/statistical_spread.rb', line 92

def population_standard_deviation
  return if values.length < 1
  Math.sqrt(StatisticalSpread.new(values).population_variance)
end

#population_variance ⇒ Object 



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# File 'lib/flash_math/modules/statistics/statistical_spread.rb', line 74

def population_variance
  return if values.length < 1
  precalculated_mean = StatisticalSpread.new(values).mean
  sum = values.inject(0) { |accumulator, value| accumulator + (value - precalculated_mean) ** 2 }
  sum / values.length.to_f
end

#range ⇒ Object 



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# File 'lib/flash_math/modules/statistics/statistical_spread.rb', line 40

def range
  return if values.length < 1
  sorted = values.sort
  sorted.last - sorted.first
end

#relative_standard_deviation ⇒ Object 



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# File 'lib/flash_math/modules/statistics/statistical_spread.rb', line 86

def relative_standard_deviation
  return if values.length < 1
  precalculated_mean = StatisticalSpread.new(values).mean
  (StatisticalSpread.new(values).population_standard_deviation / precalculated_mean) * 100.0
end

#skewness ⇒ Object 



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# File 'lib/flash_math/modules/statistics/statistical_spread.rb', line 97

def skewness
  return if values.length == 0
  return 0 if values.length == 1
  StatisticalSpread.new(values).sum_cubed_deviation / ((values.length - 1) * StatisticalSpread.new(values).cubed_standard_deviation.to_f)
end

#standard_deviation ⇒ Object 



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# File 'lib/flash_math/modules/statistics/statistical_spread.rb', line 81

def standard_deviation
  return if values.length < 2
  Math.sqrt(StatisticalSpread.new(values).variance)
end

#sum(identity = 0, &block) ⇒ Object 



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# File 'lib/flash_math/modules/statistics/statistical_spread.rb', line 3

def sum(identity=0, &block)
  if block_given?
    StatisticalSpread.new(values.map(&block)).sum(identity)
  else
    values.inject(:+) || identity
  end
end

#value_from_percentile(percentile) ⇒ Object 



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# File 'lib/flash_math/modules/statistics/statistical_spread.rb', line 61

def value_from_percentile(percentile)
  return if values.length < 1
  value_index = (percentile.to_f / 100 * values.length).ceil
  values.sort[value_index]
end

#variance ⇒ Object 



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# File 'lib/flash_math/modules/statistics/statistical_spread.rb', line 67

def variance
  return if values.length < 1
  precalculated_mean = StatisticalSpread.new(values).mean
  sum = values.inject(0) { |accumulator, value| accumulator + (value - precalculated_mean) ** 2 }
  sum / (values.length.to_f - 1)
end