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Statistics for Machine Learning

You're reading from   Statistics for Machine Learning Techniques for exploring supervised, unsupervised, and reinforcement learning models with Python and R

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Product type Paperback
Published in Jul 2017
Publisher Packt
ISBN-13 9781788295758
Length 442 pages
Edition 1st Edition
Languages
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Author (1):
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Pratap Dangeti Pratap Dangeti
Author Profile Icon Pratap Dangeti
Pratap Dangeti
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Table of Contents (10) Chapters Close

Preface 1. Journey from Statistics to Machine Learning FREE CHAPTER 2. Parallelism of Statistics and Machine Learning 3. Logistic Regression Versus Random Forest 4. Tree-Based Machine Learning Models 5. K-Nearest Neighbors and Naive Bayes 6. Support Vector Machines and Neural Networks 7. Recommendation Engines 8. Unsupervised Learning 9. Reinforcement Learning

Tuning class weights in decision tree classifier


In the following code, class weights are tuned to see the performance change in decision trees with the same parameters. A dummy DataFrame is created to save all the results of various precision-recall details of combinations:

>>> dummyarray = np.empty((6,10))
>>> dt_wttune = pd.DataFrame(dummyarray)

Metrics to be considered for capture are weight for zero and one category (for example, if the weight for zero category given is 0.2, then automatically, weight for the one should be 0.8, as total weight should be equal to 1), training and testing accuracy, precision for zero category, one category, and overall. Similarly, recall for zero category, one category, and overall are also calculated:

>>> dt_wttune.columns = ["zero_wght","one_wght","tr_accuracy", "tst_accuracy", "prec_zero","prec_one", "prec_ovll", "recl_zero","recl_one","recl_ovll"]

Weights for the zero category are verified from 0.01 to 0.5, as we know we do...

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