Book Image

NumPy Essentials

By : Leo (Liang-Huan) Chin, Tanmay Dutta, Shane Holloway
Book Image

NumPy Essentials

By: Leo (Liang-Huan) Chin, Tanmay Dutta, Shane Holloway

Overview of this book

In today’s world of science and technology, it’s all about speed and flexibility. When it comes to scientific computing, NumPy tops the list. NumPy gives you both the speed and high productivity you need. This book will walk you through NumPy using clear, step-by-step examples and just the right amount of theory. We will guide you through wider applications of NumPy in scientific computing and will then focus on the fundamentals of NumPy, including array objects, functions, and matrices, each of them explained with practical examples. You will then learn about different NumPy modules while performing mathematical operations such as calculating the Fourier Transform; solving linear systems of equations, interpolation, extrapolation, regression, and curve fitting; and evaluating integrals and derivatives. We will also introduce you to using Cython with NumPy arrays and writing extension modules for NumPy code using the C API. This book will give you exposure to the vast NumPy library and help you build efficient, high-speed programs using a wide range of mathematical features.
Table of Contents (16 chapters)
NumPy Essentials
Credits
About the Authors
About the Reviewers
www.PacktPub.com
Preface

Array data types


Data types are another important intrinsic aspect of a NumPy array alongside its memory layout and indexing. The data type of a NumPy array can be found by simply checking the dtype attribute of the array. Try out the following examples to check the data types of different arrays:

In [49]: x = np.random.random((10,10)) 
 
In [50]: x.dtype 
Out[50]: dtype('float64') 
In [51]: x = np.array(range(10)) 
 
In [52]: x.dtype 
Out[52]: dtype('int32') 
 
In [53]: x = np.array(['hello', 'world']) 
 
In [54]: x.dtype 
Out [54]: dtype('S5') 

Many array creation functions provide a default array data type. For example, the np.zeros and np.ones functions create arrays that are full of floats by default. But it is possible to make them create arrays of other data types too. Consider the following examples that demonstrate how to use the dtype argument to create arrays of arbitrary data types.

In [55]: x = np.ones((10, 10),...