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NumPy Beginner's Guide

You're reading from   NumPy Beginner's Guide An action packed guide using real world examples of the easy to use, high performance, free open source NumPy mathematical library.

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Product type Paperback
Published in Apr 2013
Publisher Packt
ISBN-13 9781782166085
Length 310 pages
Edition 2nd Edition
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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 (19) Chapters Close

Numpy Beginner's Guide Second Edition
Credits
About the Author
About the Reviewers
www.PacktPub.com
Preface
1. NumPy Quick Start FREE CHAPTER 2. Beginning with NumPy Fundamentals 3. Get in Terms with Commonly Used Functions 4. Convenience Functions for Your Convenience 5. Working with Matrices and ufuncs 6. Move Further with NumPy Modules 7. Peeking into Special Routines 8. Assure Quality with Testing 9. Plotting with Matplotlib 10. When NumPy is Not Enough – SciPy and Beyond 11. Playing with Pygame Pop Quiz Answers Index

Time for action – plotting stock volume


Stock volume varies a lot, so let’s plot it on a logarithmic scale. First we need to download historical data from Yahoo Finance, extract the dates and volume, create locators and a date formatter, create the figure, and add to it a subplot. We already went through these steps in the previous Time for action tutorial, so we will skip them here.

  1. Plot the volume using a logarithmic scale.

    plt.semilogy(dates, volume)

    Now set the locators and format the x-axis as dates. Instructions for these steps can be found in the previous Time for action tutorial as well. The stock volume using a logarithmic scale for DISH would appear as follows:

What just happened?

We plotted stock volume using a logarithmic scale (see logy.py):

from matplotlib.finance import quotes_historical_yahoo
from matplotlib.dates import DateFormatter
from matplotlib.dates import DayLocator
from matplotlib.dates import MonthLocator
import sys
from datetime import date
import matplotlib.pyplot...
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