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Data Cleaning and Exploration with Machine Learning

Data Cleaning and Exploration with Machine Learning

By : Michael Walker
4.3 (9)
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Data Cleaning and Exploration with Machine Learning

Data Cleaning and Exploration with Machine Learning

4.3 (9)
By: Michael Walker

Overview of this book

Many individuals who know how to run machine learning algorithms do not have a good sense of the statistical assumptions they make and how to match the properties of the data to the algorithm for the best results. As you start with this book, models are carefully chosen to help you grasp the underlying data, including in-feature importance and correlation, and the distribution of features and targets. The first two parts of the book introduce you to techniques for preparing data for ML algorithms, without being bashful about using some ML techniques for data cleaning, including anomaly detection and feature selection. The book then helps you apply that knowledge to a wide variety of ML tasks. You’ll gain an understanding of popular supervised and unsupervised algorithms, how to prepare data for them, and how to evaluate them. Next, you’ll build models and understand the relationships in your data, as well as perform cleaning and exploration tasks with that data. You’ll make quick progress in studying the distribution of variables, identifying anomalies, and examining bivariate relationships, as you focus more on the accuracy of predictions in this book. By the end of this book, you’ll be able to deal with complex data problems using unsupervised ML algorithms like principal component analysis and k-means clustering.
Table of Contents (23 chapters)
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1
Section 1 – Data Cleaning and Machine Learning Algorithms
5
Section 2 – Preprocessing, Feature Selection, and Sampling
9
Section 3 – Modeling Continuous Targets with Supervised Learning
13
Section 4 – Modeling Dichotomous and Multiclass Targets with Supervised Learning
19
Section 5 – Clustering and Dimensionality Reduction with Unsupervised Learning

Nonlinear SVM classification models

Although nonlinear SVC is more complicated conceptually than linear SVC, as we saw in the first section of this chapter, running a nonlinear model with scikit-learn is relatively straightforward. The main difference from a linear model is that we need to do a fair bit more hyperparameter tuning. We have to specify values for C, for gamma, and for the kernel we want to use.

While there are theoretical reasons for hypothesizing that some hyperparameter values might work better than others for a given modeling challenge, we usually resolve those values empirically, that is, with hyperparameter tuning. We try that in this section with the same NBA games data that we used in the previous section:

  1. We load the same libraries that we used in the previous section. We also import the LogisticRegression module. We will use that with a feature selection wrapper method later:
    import pandas as pd
    import numpy as np
    from sklearn.preprocessing import MinMaxScaler...

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