Book Image

Pandas Cookbook

By : Theodore Petrou
Book Image

Pandas Cookbook

By: Theodore Petrou

Overview of this book

This book will provide you with unique, idiomatic, and fun recipes for both fundamental and advanced data manipulation tasks with pandas 0.20. Some recipes focus on achieving a deeper understanding of basic principles, or comparing and contrasting two similar operations. Other recipes will dive deep into a particular dataset, uncovering new and unexpected insights along the way. The pandas library is massive, and it's common for frequent users to be unaware of many of its more impressive features. The official pandas documentation, while thorough, does not contain many useful examples of how to piece together multiple commands like one would do during an actual analysis. This book guides you, as if you were looking over the shoulder of an expert, through practical situations that you are highly likely to encounter. Many advanced recipes combine several different features across the pandas 0.20 library to generate results.
Table of Contents (12 chapters)

Filtering for states with a minority majority

In Chapter 4, Selecting Subsets of Data, we marked every row as True or False before filtering out the False rows. In a similar fashion, it is possible to mark entire groups of data as either True or False before filtering out the False groups. To do this, we first form groups with the groupby method and then apply the filter method. The filter method accepts a function that must return either True or False to indicate whether a group is kept or not.

This filter method applied after a call to the groupby method is completely different than the DataFrame filter method covered in the Selecting columns with methods recipe from Chapter 2, Essential DataFrame Operations.

Getting ready

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