Multi-DES ========

Multi-DES uses a multi-stage strategy that optimizes the parameters of the dynamic selection algorithms during the training stage to perform cross-project defect prediction. This method is centered on techniques from the DESlib¹ library, as well as machine learning algorithms available in the scikit-learn API.

Internally, Multi-DES requires some processes to be performed before training and prediction. Multi-DES requires the following:

1. Location where experiment data is stored;

2. Data pre-processing must follow a pre-established definition

• Since this method seeks to predict whether a given project is defective or not, the prediction process requires that the data have only two labels, defect and non-defect, i.e, it operates only with binary data. Also, feature bug label must be in the first column. For more details, check out the example page

3. Training and evaluation

• It is possible to use different parameters: dynamic selection techniques, different machine learning algorithms and different variations in the size of the pool for classifiers. So, all generated models use the same data processing, training and evaluation steps.

How it works?

The Multi-DES, considering the nature of cross-project defect prediction, is centered on a few key steps, such as:

1. Overproduction, based on the training set, n models are generated using a series of parameters: dynamic selection techniques, base classifiers and sizes of pool of classifiers
2. Best configuration selection, consists of defining a competent predictive model by training set to classify the test data.
3. Prediction, model evaluation process with performance evaluation metrics.

• Performance evaluation metrics

  1. F1-score
  2. Area under the curve ROC (ROC-AUC)
  3. False Alarm Probability (PF)

Results are stored in CSV files. It is worth mentioning that the Multi-DES does not carry out an additional evaluation of the results. So this needs to be created by external scripts; this approach only performs the generation of results using different experimental setups.

Requirements:

Multi-DES has been tested to work with Python 3.5 or greater. The requirements are:

• scipy(>=1.4.1)
• numpy(>=1.21.6)
• scikit-learn(>=1.0.2)
• deslib(>=0.3.5)
• glob(>=0.7)

These dependencies are automatically installed using the pip commands above.

Installation:

The package can be installed using:

Latest version (under development):

!git clone https://github.com/jsaj/Multi_DES.git

Also, need install deslib:

!pip install deslib

Example

Here we show an example using the Multi-DES with default parameters. We used the Google Colaboratory environment to run the experiments, so:

from Multi_DES.multides import MULTIDES

import pandas as pd
from glob import glob

import warnings
warnings.filterwarnings("ignore")

# path of datasets to predict
path = '/content/Multi_DES/benchmark-execution/benchmarks/datasets/RELINK/*'

# read and create dataframe (dataset) with all projects for predict
dataset = []
for project_url in glob(path):
  productName = project_url.split('/')[len(project_url.split('/'))-1].split('.csv')[0]
  df = pd.read_csv(project_url)
  df.insert(0, 'productName', productName)
  dataset.append(df)
dataset = pd.concat(dataset).reset_index(drop=True)

#create Multi-DES object to predict dataset
obj = MULTIDES(dataset)

#get Multi-DE performance after predict the dataset. Return a pandas dataframe
obj.performances

In addition to prediction with default parameters, the Multi-DES method accepts any list of dynamic selection techniques (from deslib) and list of classifiers (from scikit-learn) as input, including a list containing different size for pool of classifier.

References:

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1. Rafael M. O. Cruz, Luiz G. Hafemann, Robert Sabourin and George D. C. Cavalcanti DESlib

   A Dynamic ensemble selection library in Python. arXiv preprint arXiv:1802.04967 (2018).

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