EnsembleDiversityTests

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Simple python implementations of Diversity Measures for Classifiers

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Measures mainly from

• Combining Pattern Classifiers: Methods and Algorithms, Ludmila Kuncheva, 2004
• Conditional Accuracy Table as in Combining Information Extraction Systems Using Voting and Stacked Generalization, Sigletos et al, 2005

Python dependencies

(May need sudo rights for the following installations)

1. Install pip

apt-get install python-pip

2. Install needed python modules trhough pip

$ pip install -r requirements.txt

That’s it.

Example python usage

(Running the following in python):

from EnsembleDiversityTests import DiversityTests

pred_a = ['male', 'female', 'male']
pred_b = ['female', 'female', 'female']
pred_c = ['male','male','male']
names = ['a', 'b', 'c']
truth = ['female', 'male', 'female']
predictions_test= [pred_a,pred_b,pred_c]
test_class = DiversityTests(predictions_test, names, truth)
test_class.print_report()

Will produce:

---------------------------------------------------------------
Diversity Tests Report
---------------------------------------------------------------

Measures Details
===============================================================
Correlation: For +-1 perfect aggrement/disagreement
Q-statistic: Q=0  => Independent. For q>0 predictors find the the same results
Cohen's k: k->0  => High Disagreement => High Diversity
Kohovi-Wolpert Variance -> Inf => High Diversity
Conditional Accuracy Table: Conditional Probability that the row system predicts correctly, given
                            that the column system also predicts correctly
===============================================================
---------------------------------------------------------------

Measures Results
---------------------------------------------------------------

['get_KWVariance', 'get_avg_pairwise', 'get_conditional_acc_table']
#####  Kohovi-Wolpert Variance:  0.222  #####
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

#### Pairwise Average Metrics: #####
Avg. Cor: 0.000
Avg. Q-statistic: nan
Avg. Cohen's k: 0.000
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

###Conditional Accuracy Table###
     a    b    c
a  nan 0.00 0.00
b  nan 1.00 0.00
c  nan 0.00 1.00
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Another example on the same inputs:

from BaseLearnerDiversity.EnsembleDiversityTests import BaseClassifiers
base_C_test =  BaseClassifiers(predictions_test, names, truth)
DM = base_C_test.get_difficulty_measures()

Will produce:

Base Accuracies
a : 0.00  ||  b : 66.67  ||  c : 33.33  
Models Correct Aggrement Percentages
   Only this Model   1-model aggree   2-model aggree
a             0.00             0.00             0.00
b            66.67             0.00             0.00
c            33.33             0.00             0.00
Predictions Distributions
All correct : 0.00  || Some correct : 100.00 || All wrong: 0.00 
Not all Correct Instances Distributions
None Correct : 0.00  ||  1 correct : 100.00  ||  2 correct : 0.00  
Measure of difficulty: 	0.027777777777777783 

Remark: In the Conditioanl Accuracy Table

• nan: would denote that the column system does not make any correct prediction at all
• 0 value: would denote that the row system's correct predictions never overlap with the columns systems correct predictions.

Args for DiversityTests:

• @predictions: list of lists. Each sublist contains the predictions of a classifier
• @names: list of strings. Each string is the name of the classifier.
• @true: list of labels. Each label is the truth label

Questions/Errors

Bougiatiotis Konstantinos, NCSR ‘DEMOKRITOS’ E-mail: bogas.ko@gmail.com