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Statistics for Machine Learning

You're reading from  Statistics for Machine Learning

Product type Book
Published in Jul 2017
Publisher Packt
ISBN-13 9781788295758
Pages 442 pages
Edition 1st Edition
Languages
Concepts
Author (1):
Pratap Dangeti Pratap Dangeti
Profile icon Pratap Dangeti

Table of Contents (16) Chapters

Title Page
Credits
About the Author
About the Reviewer
www.PacktPub.com
Customer Feedback
Preface
1. Journey from Statistics to Machine Learning 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

Random forest classifier - grid search


Tuning parameters in a machine learning model plays a critical role. Here, we are showing a grid search example on how to tune a random forest model:

# Random Forest Classifier - Grid Search 
>>> from sklearn.pipeline import Pipeline 
>>> from sklearn.model_selection import train_test_split,GridSearchCV 
 
>>> pipeline = Pipeline([ ('clf',RandomForestClassifier(criterion='gini',class_weight = {0:0.3,1:0.7}))])

Tuning parameters are similar to random forest parameters apart from verifying all the combinations using the pipeline function. The number of combinations to be evaluated will be (3 x 3 x 2 x 2) *5 =36*5 = 180 combinations. Here 5 is used in the end, due to the cross validation of five-fold:

>>> parameters = { 
...         'clf__n_estimators':(2000,3000,5000), 
...         'clf__max_depth':(5,15,30), 
...         'clf__min_samples_split':(2,3), 
...         'clf__min_samples_leaf':(1,2)  } 

>>> grid_search...
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