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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 – finding highest and lowest values


The min and max functions are the answer to our requirement. Perform the following steps to find highest and lowest values:

  1. First, we will need to read our file again and store the values for the high and low prices into arrays.

    h,l=np.loadtxt('data.csv', delimiter=',', usecols=(4,5), unpack=True)

    The only thing that changed is the usecols parameter, since the high and low prices are situated in different columns.

  2. The following code gets the price range:

    print "highest =", np.max(h)
    print "lowest =", np.min(l)

    These are the values returned:

    highest = 364.9
    lowest = 333.53

    Now, it's trivial to get a midpoint, so it is left as an exercise for the reader to attempt.

  3. NumPy allows us to compute the spread of an array with a function called ptp. The ptp function returns the difference between the maximum and minimum values of an array. In other words, it is equal to max(array) - min(array). Call the ptp function.

    print "Spread high price", np.ptp(h)
    print...
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