Book Image

R Data Science Essentials

Book Image

R Data Science Essentials

Overview of this book

With organizations increasingly embedding data science across their enterprise and with management becoming more data-driven it is an urgent requirement for analysts and managers to understand the key concept of data science. The data science concepts discussed in this book will help you make key decisions and solve the complex problems you will inevitably face in this new world. R Data Science Essentials will introduce you to various important concepts in the field of data science using R. We start by reading data from multiple sources, then move on to processing the data, extracting hidden patterns, building predictive and forecasting models, building a recommendation engine, and communicating to the user through stunning visualizations and dashboards. By the end of this book, you will have an understanding of some very important techniques in data science, be able to implement them using R, understand and interpret the outcomes, and know how they helps businesses make a decision.
Table of Contents (15 chapters)
R Data Science Essentials
Credits
About the Authors
About the Reviewers
www.PacktPub.com
Preface
Index

Evaluating logistic regression


Now, after predicting the values in the test dataset, we need to compute the accuracy of the model to know where we stand. We will first combine the actual value and predicted values, and use the head function to visually see the difference between the actual and predicted values for a few of the rows. We will then convert the newly formed data into the data frame format. Based on a trial-and-error basis, we set a suitable threshold. In the following case, we consider the probabilities with a value greater than 0.7 as 1; otherwise, 0:

result<- cbind(testdata$life_expectancy_morethan_70, prediction)
result<- as.data.frame(result)
colnames(result) <- c("Actual","Prediction")
result$Predicted[result[2] > 0.7] <- 1
result$Predicted[result[2] <= 0.7] <- 0
result<-  result[ , -which(names(result) %in% c("Prediction"))]
head(result, 20)

The output is as follows:

From the preceding output, we can visualize the difference between the Actual and...