#README

This code implements the Bayesian or-of-and algorithm as described in the BOA paper. We include the tictactoe dataset in the correct formatting to be used by this code.

This code requires the external frequent itemset mining package "PyFIM," available at http://www.borgelt.net/pyfim.html

It is specific to binary classification with binary features (although could easily be extended to multiclass).

CITATION

Wang, T., Rudin, C., Doshi-Velez, F., Liu, Y., Klampfl, E., & MacNeille, P. (2017). A bayesian framework for learning rule sets for interpretable classification. The Journal of Machine Learning Research, 18(1), 2357-2393.

Wang, T., Rudin, C., Velez-Doshi, F., Liu, Y., Klampfl, E., & MacNeille, P. (2016, December). Bayesian rule sets for interpretable classification. In 2016 IEEE 16th International Conference on Data Mining (ICDM) (pp. 1269-1274). IEEE.

INPUT

The main code to be run by the user is example.py. This example.py uses input training data to generate ruled and then search for the optimal BRS using simmulated annealing. At the end of the file the true positive rate and false positive rate is computed to show the performance. Notice that the input data has to be binary coded and the column names have to have the form 'attributename_attributevalue'. If your data is not binary coded, for example attributename #color has values {red, blue, yellow}, and an item "red" can be coded as "color_red"=1, "color_blue"=0, "color_yellow"=0. (The last two are optional. Usually including the absent/negative #items improve the predicting accuracy. Our example code does not use it for simplicity)

Input files

• tictactoe_X.txt : This is the file containing the X for tictactoe data, for which all features are binary. Each line is a data entry in which all of the features with value "1" are simply listed, with spaces delimiting different items. 'attributename_attributevalue' = 1 if attributename=attributevalue. For example, '1_X=1' means the 1st #position is X.

• tictactoe_Y.txt : This file contains the Y data (labels), and contains a line corresponding to each line in tictactoe_X.txt.

Parameters

• supp : This is the minimum support of rules to be generated. We recommend a number in [5,15]
• maxlen : This is the maximum length of a pattern. We highly recommend to use 3. If maxlen is too big, the fpgrowth function will generate too many patterns which takes a lot of space and time to go through them in order to pick the best N rules
• N : The number of rules selected from all rules that are generated
• Niteration: The number of iterations in each chain in simmulated annealing.
• Nchain : The number of chains in simmulated annealing
• alpha_1,beta_1,alpha_2,beta_2,alpha_l,beta_l: correspond to alpha_+,beta_+,alpha_-, beta_-,alpha_l and beta_l in the paper. The general principle of setting these parameters is: 1) alpha_1/beta_1 need to be close to one and alpha_2/beta_2 need to be close to 0. 2) Changing the sum alpha_1, beta_1 and the sum of alpha_2, beta_2 will generate different points on a ROC curve

OUTPUT

The function generate_rules generates patterns that satisfy the minimum support and maximum length and then select the Nrules rules that have the highest entropy. In function SA_patternbased, each local maximum is stored in maps and the best BOA is returned. Remember here the BOA contains only the index of selected rules from Nrules self.rules