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Python Data Analysis - Third Edition

You're reading from  Python Data Analysis - Third Edition

Product type Book
Published in Feb 2021
Publisher Packt
ISBN-13 9781789955248
Pages 478 pages
Edition 3rd Edition
Languages
Authors (2):
Avinash Navlani Avinash Navlani
Profile icon Avinash Navlani
Ivan Idris Ivan Idris
Profile icon Ivan Idris
View More author details
Toc

Table of Contents (20) Chapters close

Preface 1. Section 1: Foundation for Data Analysis
2. Getting Started with Python Libraries 3. NumPy and pandas 4. Statistics 5. Linear Algebra 6. Section 2: Exploratory Data Analysis and Data Cleaning
7. Data Visualization 8. Retrieving, Processing, and Storing Data 9. Cleaning Messy Data 10. Signal Processing and Time Series 11. Section 3: Deep Dive into Machine Learning
12. Supervised Learning - Regression Analysis 13. Supervised Learning - Classification Techniques 14. Unsupervised Learning - PCA and Clustering 15. Section 4: NLP, Image Analytics, and Parallel Computing
16. Analyzing Textual Data 17. Analyzing Image Data 18. Parallel Computing Using Dask 19. Other Books You May Enjoy

Working with missing values

Most real-world datasets are messy and noisy. Due to their messiness and noise, lots of values are either faulty or missing. pandas offers lots of built-in functions to deal with missing values in DataFrames:

  • Check missing values in a DataFrame: pandas' isnull() function checks for the existence of null values and returns True or False, where True is for null and False is for not-null values. The sum() function will sum all the True values and returns the count of missing values. We have tried two ways to count the missing values; both show the same output:
# Count missing values in DataFrame
pd.isnull(df).sum()

The following is the second method:

df.isnull().sum()

This results in the following output:

  • Drop missing values: A very naive approach to deal with missing values is to drop them for analysis purposes. pandas has the dropna() function to drop or delete such observations from the DataFrame. Here, the inplace=True attribute makes the changes in...
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