Book Image

Pandas 1.x Cookbook - Second Edition

By : Matt Harrison, Theodore Petrou
Book Image

Pandas 1.x Cookbook - Second Edition

By: Matt Harrison, Theodore Petrou

Overview of this book

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 as one would do during an actual analysis. This book guides you, as if you were looking over the shoulder of an expert, through situations that you are highly likely to encounter. This new updated and revised edition provides you with unique, idiomatic, and fun recipes for both fundamental and advanced data manipulation tasks with pandas. 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. Many advanced recipes combine several different features across the pandas library to generate results.
Table of Contents (17 chapters)
15
Other Books You May Enjoy
16
Index

Exploding indexes

The previous recipe walked through a trivial example of two small Series being added together with unequal indexes. This recipe is more of an "anti-recipe" of what not to do. The Cartesian product of index alignment can produce comically incorrect results when dealing with larger amounts of data.

In this recipe, we add two larger Series that have indexes with only a few unique values but in different orders. The result will explode the number of values in the indexes.

How to do it…

  1. Read in the employee data and set the index to the RACE column:
    >>> employee = pd.read_csv(
    ...     "data/employee.csv", index_col="RACE"
    ... )
    >>> employee.head()
                  UNIQUE_ID POSITION_TITLE  ...   HIRE_DATE    JOB_DATE
    RACE                                    ...                        
    Hispanic/...          0  ASSISTAN...    ...  2006-06-12  2012-10-13
    Hispanic/...          1  LIBRARY ...   ...