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

Memory layout of ndarray


A particularly interesting attribute of the ndarray object is flags. Type the following code:

In [12]: x.flags 

It should produce something like this:

Out[12]: 
  C_CONTIGUOUS : True 
  F_CONTIGUOUS : False 
  OWNDATA : True 
  WRITEABLE : True 
  ALIGNED : True 
  UPDATEIFCOPY : False 

The flags attribute holds information about the memory layout of the array. The C_CONTIGUOUS field in the output indicates whether the array was a C-style array. This means that the indexing of this array is done like a C array. This is also called row-major indexing in the case of 2D arrays. This means that, when moving through the array, the row index is incremented first, and then the column index is incremented. In the case of a multidimensional C-style array, the last dimension is incremented first, followed by the last but one, and so on.

Similarly, the F_CONTIGUOUS attribute indicates whether the array is a Fortran-style array. Such an array...