Book Image

NumPy Cookbook

Book Image

NumPy Cookbook

Overview of this book

Today's world of science and technology is all about speed and flexibility. When it comes to scientific computing, NumPy is on the top of the list. NumPy will give you both speed and high productivity. "NumPy Cookbook" will teach you all about NumPy, a leading scientific computing library. NumPy replaces a lot of the functionality of Matlab and Mathematica, but in contrast to those products, it is free and open source. "Numpy Cookbook" will teach you to write readable, efficient, and fast code that is as close to the language of Mathematics as much as possible with the cutting edge open source NumPy software library. You will learn about installing and using NumPy and related concepts. At the end of the book, we will explore related scientific computing projects. This book will give you a solid foundation in NumPy arrays and universal functions. You will also learn about plotting with Matplotlib and the related SciPy project through examples. "NumPy Cookbook" will help you to be productive with NumPy and write clean and fast code.
Table of Contents (17 chapters)
NumPy Cookbook
About the Author
About the Reviewers

Resizing images

In this recipe, we will load a sample image of Lena, which is available in the SciPy distribution, into an array. This chapter is not about image manipulation, by the way; we will just use the image data as an input.


Lena Soderberg appeared in a 1972 Playboy magazine. For historical reasons, one of those images is often used in the field of image processing. Don't worry; the picture in question is completely safe for work.

We will resize the image using the repeat function. This function repeats an array, which in practice means resizing the image by a certain factor.

Getting ready

A prerequisite for this recipe is to have SciPy, Matplotlib, and PIL installed. Have a look at the corresponding recipes in this chapter and the previous chapter.

How to do it...

  1. Load the Lena image into an array.

    SciPy has a lena function, which can load the image into a NumPy array:

    lena = scipy.misc.lena()

    Some refactoring has occurred since version 0.10, so if you are using an older version, the...