Book Image

Practical Data Science Cookbook

By : Tony Ojeda, Sean Patrick Murphy, Benjamin Bengfort, Abhijit Dasgupta
Book Image

Practical Data Science Cookbook

By: Tony Ojeda, Sean Patrick Murphy, Benjamin Bengfort, Abhijit Dasgupta

Overview of this book

<p>As increasing amounts of data is generated each year, the need to analyze and operationalize it is more important than ever. Companies that know what to do with their data will have a competitive advantage over companies that don't, and this will drive a higher demand for knowledgeable and competent data professionals.</p> <p>Starting with the basics, this book will cover how to set up your numerical programming environment, introduce you to the data science pipeline (an iterative process by which data science projects are completed), and guide you through several data projects in a step-by-step format. By sequentially working through the steps in each chapter, you will quickly familiarize yourself with the process and learn how to apply it to a variety of situations with examples in the two most popular programming languages for data analysis—R and Python.</p>
Table of Contents (18 chapters)
Practical Data Science Cookbook
Credits
About the Authors
About the Reviewers
www.PacktPub.com
Preface
Index

Training the SVD-based model


We're now ready to write our functions that factor our training dataset and build our recommender model. You can see the required functions in this recipe.

How to do it…

We construct the following functions to train our model. Note that these functions are not part of the Recommender class:

def initialize(R, K):
     """
     Returns initial matrices for an N X M matrix, 
     R and K features.

     :param R: the matrix to be factorized
     :param K: the number of latent features

     :returns: P, Q initial matrices of N x K and M x K sizes
     """
     N, M = R.shape
     P = np.random.rand(N,K)
     Q = np.random.rand(M,K)

     return P, Q

 def factor(R, P=None, Q=None, K=2, steps=5000, alpha=0.0002, beta=0.02):
     """
     Performs matrix factorization on R with given parameters.

     :param R: A matrix to be factorized, dimension N x M
     :param P: an initial matrix of dimension N x K
     :param Q: an initial matrix of dimension M x K
     :param...