Book Image

Python Data Analysis - Second Edition

By : Ivan Idris
Book Image

Python Data Analysis - Second Edition

By: Ivan Idris

Overview of this book

Data analysis techniques generate useful insights from small and large volumes of data. Python, with its strong set of libraries, has become a popular platform to conduct various data analysis and predictive modeling tasks. With this book, you will learn how to process and manipulate data with Python for complex analysis and modeling. We learn data manipulations such as aggregating, concatenating, appending, cleaning, and handling missing values, with NumPy and Pandas. The book covers how to store and retrieve data from various data sources such as SQL and NoSQL, CSV fies, and HDF5. We learn how to visualize data using visualization libraries, along with advanced topics such as signal processing, time series, textual data analysis, machine learning, and social media analysis. The book covers a plethora of Python modules, such as matplotlib, statsmodels, scikit-learn, and NLTK. It also covers using Python with external environments such as R, Fortran, C/C++, and Boost libraries.
Table of Contents (22 chapters)
Python Data Analysis - Second Edition
Credits
About the Author
About the Reviewers
www.PacktPub.com
Customer Feedback
Preface
Key Concepts
Online Resources

Handling missing values


We regularly encounter empty fields in data records. It's best that we accept this and learn how to handle this kind of issue in a robust manner. Real data can not only have gaps-it can also have wrong values, because of faulty measuring equipment, for example. In Pandas, missing numerical values will be designated as NaN, objects as None, and the datetime64 objects as NaT. The outcome of arithmetic operations with NaN values is also NaN. Descriptive statistics methods, such as summation and average, behave differently. As we observed in an earlier example, in such a case, NaN values are treated as zero values. However, if all the values are NaN during, say, summation, the sum returned is still NaN. In aggregation operations, NaN values in the column that we group are ignored. We will again load the WHO_first9cols.csv file into a DataFrame. Remember that this file contains empty fields. Let's only select the first three rows, including the headers of the Country and...