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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

Examining logistic regression errors with a confusion matrix

Getting ready

Import and view the confusion matrix for the logistic regression we constructed:

from sklearn.metrics import confusion_matrix
confusion_matrix(y_test, y_pred,labels = [1,0])

array([[27, 27],
[12, 88]])

I passed three arguments to the confusion matrix:

  • y_test: The test target set
  • y_pred: Our logistic regression predictions
  • labels: References to a positive class

The labels = [1,0] means that the positive class is 1 and the negative class is 0. In the medical context, we found while exploring the Pima Indians diabetes dataset that class 1 tested positive for diabetes.

Here is the confusion matrix, again in pandas dataframe form:

...
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