Book Image

Data Science Using Python and R

By : Chantal D. Larose, Daniel T. Larose
Book Image

Data Science Using Python and R

By: Chantal D. Larose, Daniel T. Larose

Overview of this book

Data science is hot. Bloomberg named a data scientist as the ‘hottest job in America’. Python and R are the top two open-source data science tools using which you can produce hands-on solutions to real-world business problems, using state-of-the-art techniques. Each chapter in the book presents step-by-step instructions and walkthroughs for solving data science problems using Python and R. You’ll learn how to prepare data, perform exploratory data analysis, and prepare to model the data. As you progress, you’ll explore what are decision trees and how to use them. You’ll also learn about model evaluation, misclassification costs, naïve Bayes classification, and neural networks. The later chapters provide comprehensive information about clustering, regression modeling, dimension reduction, and association rules mining. The book also throws light on exciting new topics, such as random forests and general linear models. The book emphasizes data-driven error costs to enhance profitability, which avoids the common pitfalls that may cost a company millions of dollars. By the end of this book, you’ll have enough knowledge and confidence to start providing solutions to data science problems using R and Python.
Table of Contents (20 chapters)
Free Chapter
1
ABOUT THE AUTHORS
17
INDEX
18
END USER LICENSE AGREEMENT

12.10 HOW TO PERFORM PRINCIPAL COMPONENTS ANALYSIS USING R

Import the clothing_store_PCA_training and clothing_store_PCA_test data sets as clothes_train and clothes_test, respectively. To simplify code that comes later, we will separate the training and test data into X and y variables.

y <‐ clothes_train$Sales.per.Visit
X <‐ clothes_train[, c(1:5)]
X_test <‐ clothes_test[, c(1:5)]

Remember to standardize the predictor variables.

X_z <‐ as.data.frame(scale(X))
colnames(X_z) <‐ c("Days.since.Purchase.Z", "Purchase.Visits.Z", "Days.on.File.Z",
     "Days.between.Purchases.Z", "Diff.Items.Purchased.Z")

To obtain the correlation matrix, we use the cor() command.

round(cor(X_z), 3)

The cor() command, with the predictor variables X_z as input, is placed inside the round() command. The second input of the round() command is the number of significant digits the answers will be rounded...