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Getting Started with Python Data Analysis

You're reading from  Getting Started with Python Data Analysis

Product type Book
Published in Nov 2015
Publisher
ISBN-13 9781785285110
Pages 188 pages
Edition 1st Edition
Languages

Table of Contents (15) Chapters

Getting Started with Python Data Analysis
Credits
About the Authors
About the Reviewers
www.PacktPub.com
Preface
Introducing Data Analysis and Libraries NumPy Arrays and Vectorized Computation Data Analysis with Pandas Data Visualization Time Series Interacting with Databases Data Analysis Application Examples Machine Learning Models with scikit-learn Index

Linear algebra with NumPy


Linear algebra is a branch of mathematics concerned with vector spaces and the mappings between those spaces. NumPy has a package called linalg that supports powerful linear algebra functions. We can use these functions to find eigenvalues and eigenvectors or to perform singular value decomposition:

>>> A = np.array([[1, 4, 6],
    [5, 2, 2],
    [-1, 6, 8]])
>>> w, v = np.linalg.eig(A)
>>> w                           # eigenvalues
array([-0.111 + 1.5756j, -0.111 – 1.5756j, 11.222+0.j])
>>> v                           # eigenvector
array([[-0.0981 + 0.2726j, -0.0981 – 0.2726j, 0.5764+0.j],
    [0.7683+0.j, 0.7683-0.j, 0.4591+0.j],
    [-0.5656 – 0.0762j, -0.5656 + 0.00763j, 0.6759+0.j]])

The function is implemented using the geev Lapack routines that compute the eigenvalues and eigenvectors of general square matrices.

Another common problem is solving linear systems such as Ax = b with A as a matrix and x and b as vectors. The...

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