Python Data Science Handbook

Introduktion

IPython: Beyond Normal Python8 Ämnen

Introduction to NumPy9 Ämnen

Understanding Data Types in Python

The Basics of NumPy Arrays

Computation on NumPy Arrays: Universal Functions

Aggregations: Min, Max, and Everything In Between

Computation on Arrays: Broadcasting

Comparisons, Masks, and Boolean Logic

Fancy Indexing

Sorting Arrays

Structured Data: NumPy's Structured Arrays

Understanding Data Types in Python

Data Manipulation with Pandas13 Ämnen

Introducing Pandas Objects

Data Indexing and Selection

Operating on Data in Pandas

Handling Missing Data

Hierarchical Indexing

Combining Datasets: Concat and Append

Combining Datasets: Merge and Join

Aggregation and Grouping

Pivot Tables

Vectorized String Operations

Working with Time Series

HighPerformance Pandas: eval() and query()

Further Resources

Introducing Pandas Objects

Visualization with Matplotlib15 Ämnen

Simple Line Plots

Simple Scatter Plots

Visualizing Errors

Density and Contour Plots

Histograms, Binnings, and Density

Customizing Plot Legends

Customizing Colorbars

Multiple Subplots

Text and Annotation

Customizing Ticks

Customizing Matplotlib: Configurations and Stylesheets

ThreeDimensional Plotting in Matplotlib

Geographic Data with Basemap

Visualization with Seaborn

Further Resources

Simple Line Plots

Machine Learning15 Ämnen

What Is Machine Learning?

Introducing ScikitLearn

Hyperparameters and Model Validation

Feature Engineering

In Depth: Naive Bayes Classification

In Depth: Linear Regression

InDepth: Support Vector Machines

InDepth: Decision Trees and Random Forests

In Depth: Principal Component Analysis

InDepth: Manifold Learning

In Depth: kMeans Clustering

In Depth: Gaussian Mixture Models

InDepth: Kernel Density Estimation

Application: A Face Detection Pipeline

Further Machine Learning Resources

What Is Machine Learning?

Appendix: Figure Code
Machine Learning
juli 27, 2021
In many ways, machine learning is the primary means by which data science manifests itself to the broader world. Machine learning is where these computational and algorithmic skills of data science meet the statistical thinking of data science, and the result is a collection of approaches to inference and data exploration that are not about effective theory so much as effective computation.
The term “machine learning” is sometimes thrown around as if it is some kind of magic pill: apply machine learning to your data, and all your problems will be solved! As you might expect, the reality is rarely this simple. While these methods can be incredibly powerful, to be effective they must be approached with a firm grasp of the strengths and weaknesses of each method, as well as a grasp of general concepts such as bias and variance, overfitting and underfitting, and more.
This chapter will dive into practical aspects of machine learning, primarily using Python’s ScikitLearn package. This is not meant to be a comprehensive introduction to the field of machine learning; that is a large subject and necessitates a more technical approach than we take here. Nor is it meant to be a comprehensive manual for the use of the ScikitLearn package (for this, you can refer to the resources listed in Further Machine Learning Resources). Rather, the goals of this chapter are:
 To introduce the fundamental vocabulary and concepts of machine learning.
 To introduce the ScikitLearn API and show some examples of its use.
 To take a deeper dive into the details of several of the most important machine learning approaches, and develop an intuition into how they work and when and where they are applicable.
Much of this material is drawn from the ScikitLearn tutorials and workshops I have given on several occasions at PyCon, SciPy, PyData, and other conferences. Any clarity in the following pages is likely due to the many workshop participants and coinstructors who have given me valuable feedback on this material over the years!
Finally, if you are seeking a more comprehensive or technical treatment of any of these subjects, I’ve listed several resources and references in Further Machine Learning Resources.