Book Image

NumPy: Beginner's Guide

By : Ivan Idris
Book Image

NumPy: Beginner's Guide

By: Ivan Idris

Overview of this book

Table of Contents (21 chapters)
NumPy Beginner's Guide Third Edition
Credits
About the Author
About the Reviewers
www.PacktPub.com
Preface
NumPy Functions' References
Index

Time for action – using searchsorted


The searchsorted() function gets the index of a value in a sorted array. An example should make this clear:

  1. To demonstrate, create an array with arange(), which of course is sorted:

    a = np.arange(5)
  2. Time to call the searchsorted() function:

    indices = np.searchsorted(a, [-2, 7])
    print("Indices", indices)

    The indices, which should maintain the sort order:

    Indices [0 5]
    
  3. Construct the full array with the insert() function:

    print("The full array", np.insert(a, indices, [-2, 7]))

    This gives us the full array:

    The full array [-2  0  1  2  3  4  7]
    

What just happened?

The searchsorted() function gave us indices 5 and 0 for 7 and -2. With these indices, we made the array [-2, 0, 1, 2, 3, 4, 7], so the array remains sorted (see sortedsearch.py):

from __future__ import print_function
import numpy as np

a = np.arange(5)
indices = np.searchsorted(a, [-2, 7])
print("Indices", indices)

print("The full array", np.insert(a, indices, [-2, 7]))