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scikit-learn Cookbook - Second Edition

You're reading from  scikit-learn Cookbook - Second Edition

Product type Book
Published in Nov 2017
Publisher Packt
ISBN-13 9781787286382
Pages 374 pages
Edition 2nd Edition
Languages
Author (1):
Trent Hauck Trent Hauck
Profile icon Trent Hauck

Table of Contents (13) Chapters

Preface 1. High-Performance Machine Learning – NumPy 2. Pre-Model Workflow and Pre-Processing 3. Dimensionality Reduction 4. Linear Models with scikit-learn 5. Linear Models – Logistic Regression 6. Building Models with Distance Metrics 7. Cross-Validation and Post-Model Workflow 8. Support Vector Machines 9. Tree Algorithms and Ensembles 10. Text and Multiclass Classification with scikit-learn 11. Neural Networks 12. Create a Simple Estimator

K-fold cross validation

In the quest to find the best model, you can view the indices of cross-validation folds and see what data is in each fold.

Getting ready

Create a toy dataset that is very small:

import numpy as np
X = np.array([[1, 2], [3, 4], [5, 6], [7, 8],[1, 2], [3, 4], [5, 6], [7, 8]])
y = np.array([1, 2, 1, 2, 1, 2, 1, 2])

How to do it..

  1. Import KFold and select the number of splits:
from sklearn.model_selection import KFold

kf= KFold(n_splits = 4)
  1. You can iterate through the generator and print out the indices:
cc = 1
for train_index, test_index in kf.split...
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