Class: AdaBoost::ContingencyTable

Inherits:
Object
  • Object
show all
Defined in:
lib/adaboost/contingency_table.rb

Instance Method Summary collapse

Constructor Details

#initialize ⇒ ContingencyTable

Returns a new instance of ContingencyTable.



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# File 'lib/adaboost/contingency_table.rb', line 5

def initialize
  @table = [[0, 0], [0, 0]]
end

Instance Method Details

#accuracy ⇒ Object 



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# File 'lib/adaboost/contingency_table.rb', line 93

def accuracy
  (true_positive + true_negative) / total_population.to_f
end

#add_prediction(y, h) ⇒ Object 



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# File 'lib/adaboost/contingency_table.rb', line 25

def add_prediction(y, h)
  @table[class_to_index(y)][class_to_index(h)] += 1
end

#class_to_index(k) ⇒ Object 



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# File 'lib/adaboost/contingency_table.rb', line 178

def class_to_index(k)
  (k > 0) ? 1 : 0
end

#condition_negative ⇒ Object 



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# File 'lib/adaboost/contingency_table.rb', line 53

def condition_negative
  false_positive + true_negative
end

#condition_positive ⇒ Object 



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# File 'lib/adaboost/contingency_table.rb', line 49

def condition_positive
  true_positive + false_negative
end

#diagnostic_odds_ratio ⇒ Object 



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# File 'lib/adaboost/contingency_table.rb', line 125

def diagnostic_odds_ratio
  positive_likelihood_ratio / negative_likelihood_ratio.to_f
end

#fall_out ⇒ Object 



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# File 'lib/adaboost/contingency_table.rb', line 77

def fall_out
  false_positive_rate
end

#false_discovery_rate ⇒ Object 



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# File 'lib/adaboost/contingency_table.rb', line 105

def false_discovery_rate
  false_positive / outcome_positive.to_f
end

#false_negative ⇒ Object 



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# File 'lib/adaboost/contingency_table.rb', line 21

def false_negative
  @table[1][0]
end

#false_negative_rate ⇒ Object 



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# File 'lib/adaboost/contingency_table.rb', line 81

def false_negative_rate
  false_negative / condition_positive.to_f
end

#false_omission_rate ⇒ Object 



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# File 'lib/adaboost/contingency_table.rb', line 109

def false_omission_rate
  false_negative / outcome_negative.to_f
end

#false_positive ⇒ Object 



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# File 'lib/adaboost/contingency_table.rb', line 13

def false_positive
  @table[0][1]
end

#false_positive_rate ⇒ Object 



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# File 'lib/adaboost/contingency_table.rb', line 73

def false_positive_rate
  false_positive / condition_negative.to_f
end

#negative_likelihood_ratio ⇒ Object 



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# File 'lib/adaboost/contingency_table.rb', line 121

def negative_likelihood_ratio
  false_negative_rate / true_negative_rate.to_f
end

#negative_predictive_value ⇒ Object 



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# File 'lib/adaboost/contingency_table.rb', line 113

def negative_predictive_value
  true_negative / outcome_negative.to_f
end

#outcome_negative ⇒ Object 



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# File 'lib/adaboost/contingency_table.rb', line 33

def outcome_negative
  true_negative + false_negative
end

#outcome_positive ⇒ Object 



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# File 'lib/adaboost/contingency_table.rb', line 29

def outcome_positive
  true_positive + false_positive
end

#positive_likelihood_ratio ⇒ Object 



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# File 'lib/adaboost/contingency_table.rb', line 117

def positive_likelihood_ratio
  true_positive_rate / false_positive_rate.to_f
end

#positive_predictive_value ⇒ Object 



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# File 'lib/adaboost/contingency_table.rb', line 97

def positive_predictive_value
  true_positive / outcome_positive.to_f
end

#precision ⇒ Object 



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# File 'lib/adaboost/contingency_table.rb', line 101

def precision
  positive_predictive_value
end

#predicted_condition_negative ⇒ Object 



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# File 'lib/adaboost/contingency_table.rb', line 45

def predicted_condition_negative
  false_negative + true_negative
end

#predicted_condition_positive ⇒ Object 



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# File 'lib/adaboost/contingency_table.rb', line 41

def predicted_condition_positive
  true_positive + false_positive
end

#prevalence ⇒ Object 



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# File 'lib/adaboost/contingency_table.rb', line 57

def prevalence
  condition_positive / total_population.to_f
end

#recall ⇒ Object 



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# File 'lib/adaboost/contingency_table.rb', line 65

def recall
  true_positive_rate
end

#sensitivity ⇒ Object 



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# File 'lib/adaboost/contingency_table.rb', line 69

def sensitivity
  true_positive_rate
end

#specificity ⇒ Object 



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# File 'lib/adaboost/contingency_table.rb', line 89

def specificity
  true_negative_rate
end

#to_s ⇒ Object 



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# File 'lib/adaboost/contingency_table.rb', line 129

def to_s
  "\nTotal population: %d\t \
  \nCondition positive: %d\t \
  \nCondition negative: %d\t \
  \nPredicted Condition positive: %d\t \
  \nPredicted Condition negative: %d\t \
  \nTrue positive: %d\t \
  \nTrue negative: %d\t \
  \nFalse Negative: %d\t \
  \nFalse Positive: %d\t \
  \nPrevalence = Σ Condition positive / Σ Total population: %f\t \
  \nTrue positive rate (TPR) = Σ True positive / Σ Condition positive: %f\t \
  \nFalse positive rate (FPR) = Σ False positive / Σ Condition negative: %f\t \
  \nFalse negative rate (FNR) = Σ False negative / Σ Condition positive: %f\t \
  \nTrue negative rate (TNR) = Σ True negative / Σ Condition negative: %f\t \
  \nAccuracy (ACC) = Σ True positive \ Σ True negative / Σ Total population: %f\t \
  \nPositive predictive value (PPV) = Σ True positive / Σ Test outcome positive: %f\t \
  \nFalse discovery rate (FDR) = Σ False positive / Σ Test outcome positive: %f\t \
  \nFalse omission rate (FOR) = Σ False negative / Σ Test outcome negative: %f\t \
  \nNegative predictive value (NPV) = Σ True negative / Σ Test outcome negative: %f\t \
  \nPositive likelihood ratio (LR\) = TPR / FPR: %f\t \
  \nNegative likelihood ratio (LR−) = FNR / TNR: %f\t \
  \nDiagnostic odds ratio (DOR) = LR+ / LR−: %f\t" %
  [
    total_population,
    condition_positive,
    condition_negative,
    predicted_condition_positive,
    predicted_condition_negative,
    true_positive,
    true_negative,
    false_negative,
    false_positive,
    prevalence,
    true_positive_rate,
    false_positive_rate,
    false_negative_rate,
    true_negative_rate,
    accuracy,
    positive_predictive_value,
    false_discovery_rate,
    false_omission_rate,
    negative_predictive_value,
    positive_likelihood_ratio,
    negative_likelihood_ratio,
    diagnostic_odds_ratio
  ]
end

#total_population ⇒ Object 



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# File 'lib/adaboost/contingency_table.rb', line 37

def total_population
  @table[0][0] + @table[0][1] + @table[1][0] + @table[1][1]
end

#true_negative ⇒ Object 



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# File 'lib/adaboost/contingency_table.rb', line 17

def true_negative
  @table[0][0]
end

#true_negative_rate ⇒ Object 



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# File 'lib/adaboost/contingency_table.rb', line 85

def true_negative_rate
  true_negative / condition_negative.to_f
end

#true_positive ⇒ Object 



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# File 'lib/adaboost/contingency_table.rb', line 9

def true_positive
  @table[1][1]
end

#true_positive_rate ⇒ Object 



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# File 'lib/adaboost/contingency_table.rb', line 61

def true_positive_rate
  true_positive / condition_positive.to_f
end