WisardClassifier

Machine learning supervised method for classification using WiSARD

Authors: Maurizio Giordano and Massimo De Gregorio

• Istituto di Calcolo e Reti ad Alte Prestazioni (ICAR) - Consiglio Nazionale delle Ricerche (CNR) (Italy)
• Istituto di Scienze Applicate e Sistemi Intelligenti "Eduardo Caianiello" (ISASI) - Consiglio Nazionale delle Ricerche (CNR) (Italy)

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Description

WisardClassifier is a machine learning classifer implemented as an exntension module of the scikit-learn package in Python. As a consequence, to use WisardClassifier you need the following packages installed in your Python environment:

1. Numpy

2. Scikit-Learn

WisardClassifier is a classifier method for machine learning accepting as input most common data formats, such as ARFF, LibSVM, and CSV.

WisardClassifier uses WiSARD, a weighless neural network model of computation which learns and recognize binary inpiut patterns. For more details about this model please refer (and cite) to:

@article{DEGREGORIO2018338,
title = "An experimental evaluation of weightless neural networks for multi-class classification",
journal = "Applied Soft Computing",
volume = "72",
pages = "338 - 354",
year = "2018",
issn = "1568-4946",
doi = "https://doi.org/10.1016/j.asoc.2018.07.052",
url = "http://www.sciencedirect.com/science/article/pii/S156849461830440X",
author = "Massimo De Gregorio and Maurizio Giordano",
keywords = "Weightless neural network, WiSARD, Machine learning"
}

WiSARD implementation in C++ is included in sources in this distribution. The file wisard_wrapper.pyx is a cython wrapper for the integration WiSARD functions in Python. You can use and program WiSARD in Python by simply importing in your python scripts the wisard_wrapper module. An example of the use of WiSARD in Python is discussed in the section "Testing WiSARD in Python".

WisardClassifier is a Python implementation of a classifier based on WiSARD capabilities. The classifier is designed to be compliant with the Scikit-Learn interface definition. WisardClassifier main class, methods and facilities are implemented in the wisard.py script.

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Build and setup (Linux, Mac OSX)

To build the code and setup in python (locally) you just need to execute:

$ python setup.py build_ext --inplace

This will produce the WiSARD wrapper library wit name: wisard_wrapper.<dllext> where <dllext> is the library extension (so for Mac and Linux, dll for Windows).

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Testing WiSARD in Python

To use the WiSARD in your Python scripts you need to have python 2.7 (or later) installed on your system, plus the following modules:

1. Numpy (http://www.numpy.org)

2. Cython (http://cython.org)

3. matplotlib (optional) (https://matplotlib.org)

Please refer to the documentation of these packages for installation.

Once you have set the python programming framework, you can use the file test.py simple script to start using WiSARD in python.

from wisard_wrapper import *
import numpy as np

def mk_tuple(discr, sample):
    map = discr.getMapping()
    n_bit = discr.getNBits()
    n_ram = discr.getNRams()
    intuple = np.zeros(n_ram, dtype = np.uint64)
    for i in range(n_ram):
        for j in range(n_bit):
            x = map[(i * n_bit) + j]
            intuple[i] += (2**(n_bit -1 - j))  * sample[x]
    return intuple


X = np.array([[0, 1, 0, 0, 0, 0, 0, 0],
              [0, 0, 1, 1, 1, 1, 0, 0],
              [0, 0, 1, 0, 0, 0, 1, 0],
              [1, 0, 0, 0, 0, 0, 0, 1],
              [1, 1, 0, 1, 1, 1, 1, 1],
              [1, 0, 0, 0, 0, 0, 0, 0],
              [0, 0, 0, 0, 1, 0, 0, 1],
              [1, 0, 0, 0, 0, 0, 0, 1]], np.int32)

y = np.array(["A","A","B","B","A","A","B","A"])

test = np.array([0, 0, 1, 0, 0, 0, 1, 0], np.int32)

# init WiSARD (create discriminator for each class "A" and "B")
wisard = {}
wisard["A"] = PyDiscriminator(2,8)
wisard["B"] = PyDiscriminator(2,8)

# train WiSARD
for s in range(X.shape[0]):
    tuple = mk_tuple(wisard[y[s]],X[s])
    print(tuple)
    wisard[y[s]].TrainByTuple(tuple)

# print WiSARD state
print(wisard["A"].toString())
print(wisard["B"].toString())
    
# predict by WiSARD
responses = {}
test_tuple = mk_tuple(wisard["A"],test)
responses["A"] = wisard["A"].ClassifyByTuple(test_tuple)
test_tuple = mk_tuple(wisard["B"],test)
responses["B"] = wisard["B"].ClassifyByTuple(test_tuple)
print("A responds with score %.2f\n"%responses["A"])
print("B responds with score %.2f\n"%responses["B"])

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Testing WisardClassifier in Python (Scikit Learn)

To use WisardClassifier in Scikit Learn Python library you need the following packages:

1. Scipy (https://www.scipy.org)

2. Scikit Learn (http://scikit-learn.org)

Please refer to the documentation of these packages for installation.

In this package a python script wisard_classifier.py is distributed to let users execute WisardClassifier in python

$ python wisard_classifier.py -i <dataset>

Where <dataset> can be any data file in ARFF, LibSVM, or CSV format.

For a complete list of script parameters you can read the command help:

python2.7 wisard_classifier.py -h

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Testing WisardClassifier on KEEL datasets

You can test WisardClassifier on a large set of classification problems you find in the keel-datasets folder. Problem datasets were obtained from the KEEL archive (http://sci2s.ugr.es/keel/datasets.php) and transformed in LibSVM format.

As an example, to test WisardClassifier on the 'wine' dataset with 32 bits and with a resolution of data discretization of 2018 distinct values, simply run:

$ python wisard_classifier.py -b 32 -z 2018 -i KEEL-datasets/wine.libsvm