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Python Data Analysis, Second Edition

You're reading from   Python Data Analysis, Second Edition Data manipulation and complex data analysis with Python

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Product type Paperback
Published in Mar 2017
Publisher Packt
ISBN-13 9781787127487
Length 330 pages
Edition 2nd Edition
Languages
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Author (1):
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Ivan Idris Ivan Idris
Author Profile Icon Ivan Idris
Ivan Idris
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Table of Contents (16) Chapters Close

Preface 1. Getting Started with Python Libraries FREE CHAPTER 2. NumPy Arrays 3. The Pandas Primer 4. Statistics and Linear Algebra 5. Retrieving, Processing, and Storing Data 6. Data Visualization 7. Signal Processing and Time Series 8. Working with Databases 9. Analyzing Textual Data and Social Media 10. Predictive Analytics and Machine Learning 11. Environments Outside the Python Ecosystem and Cloud Computing 12. Performance Tuning, Profiling, and Concurrency A. Key Concepts
B. Useful Functions C. Online Resources

Preprocessing

Library scikit-learn has a preprocessing module, which is the topic of this section. In the previous chapter, Chapter 9, Analyzing Textual Data and Social Media, we installed scikit-learn, and we practiced a form of data preprocessing by filtering out stopwords. Some machine learning algorithms have trouble with data that is not distributed as a Gaussian with a mean of 0 and a variance of 1. The sklearn.preprocessing module takes care of this issue. We will be demonstrating it in this section. We will preprocess the meteorological data from the Dutch KNMI institute (original data for De Bilt weather station from http://www.knmi.nl/climatology/daily_data/datafiles3/260/etmgeg_260.zip). The data is just one column of the original datafile and contains daily rainfall values. It is stored in the .npy format discussed in Chapter 5, Retrieving, Processing, and Storing Data. We can load the data into a NumPy array. The values are integers that we have to multiply by 0.1 in order...

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