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Python Data Cleaning Cookbook

You're reading from   Python Data Cleaning Cookbook Modern techniques and Python tools to detect and remove dirty data and extract key insights

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Product type Paperback
Published in Dec 2020
Publisher Packt
ISBN-13 9781800565661
Length 436 pages
Edition 1st Edition
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Authors (2):
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Michael B Walker Michael B Walker
Author Profile Icon Michael B Walker
Michael B Walker
Michael Walker Michael Walker
Author Profile Icon Michael Walker
Michael Walker
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Table of Contents (12) Chapters Close

Preface 1. Chapter 1: Anticipating Data Cleaning Issues when Importing Tabular Data into pandas 2. Chapter 2: Anticipating Data Cleaning Issues when Importing HTML and JSON into pandas FREE CHAPTER 3. Chapter 3: Taking the Measure of Your Data 4. Chapter 4: Identifying Missing Values and Outliers in Subsets of Data 5. Chapter 5: Using Visualizations for the Identification of Unexpected Values 6. Chapter 6: Cleaning and Exploring Data with Series Operations 7. Chapter 7: Fixing Messy Data when Aggregating 8. Chapter 8: Addressing Data Issues When Combining DataFrames 9. Chapter 9: Tidying and Reshaping Data 10. Chapter 10: User-Defined Functions and Classes to Automate Data Cleaning 11. Other Books You May Enjoy

Importing CSV files

The read_csv method of the pandas library can be used to read a file with comma separated values (CSV) and load it into memory as a pandas data frame. In this recipe, we read a CSV file and address some common issues: creating column names that make sense to us, parsing dates, and dropping rows with critical missing data.

Raw data is often stored as CSV files. These files have a carriage return at the end of each line of data to demarcate a row, and a comma between each data value to delineate columns. Something other than a comma can be used as the delimiter, such as a tab. Quotation marks may be placed around values, which can be helpful when the delimiter occurs naturally within certain values, which sometimes happens with commas.

All data in a CSV file are characters, regardless of the logical data type. This is why it is easy to view a CSV file, presuming it is not too large, in a text editor. The pandas read_csv method will make an educated guess about...

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