Book Image

Practical Data Science with Python

By : Nathan George
Book Image

Practical Data Science with Python

By: Nathan George

Overview of this book

Practical Data Science with Python teaches you core data science concepts, with real-world and realistic examples, and strengthens your grip on the basic as well as advanced principles of data preparation and storage, statistics, probability theory, machine learning, and Python programming, helping you build a solid foundation to gain proficiency in data science. The book starts with an overview of basic Python skills and then introduces foundational data science techniques, followed by a thorough explanation of the Python code needed to execute the techniques. You'll understand the code by working through the examples. The code has been broken down into small chunks (a few lines or a function at a time) to enable thorough discussion. As you progress, you will learn how to perform data analysis while exploring the functionalities of key data science Python packages, including pandas, SciPy, and scikit-learn. Finally, the book covers ethics and privacy concerns in data science and suggests resources for improving data science skills, as well as ways to stay up to date on new data science developments. By the end of the book, you should be able to comfortably use Python for basic data science projects and should have the skills to execute the data science process on any data source.
Table of Contents (30 chapters)
1
Part I - An Introduction and the Basics
4
Part II - Dealing with Data
10
Part III - Statistics for Data Science
13
Part IV - Machine Learning
21
Part V - Text Analysis and Reporting
24
Part VI - Wrapping Up
28
Other Books You May Enjoy
29
Index

Sampling from data

Sampling methods and caveats are good to know as a data scientist. For example, we can use sampling to downsize a large dataset for analysis or prototyping code, we can use sampling to estimate confidence intervals, and we can use it to balance imbalanced datasets for machine learning. Let's begin with a few fundamental tenets of sampling.

The law of large numbers

The law of large numbers is a mathematical theorem, and essentially says we will approach the true mean of a random variable's outcome as we increase our number of samples. A few examples are useful here: as we roll a 6-sided dice many times, the average value of the rolls will approach 3.5, which is what we would fundamentally expect given the uniform distribution and average of the values 1-6.

In general, this means we should expect the average value of a measurement to approach an exact value with an increase in sampling, assuming the underlying process is random and follows some...