Book Image

R for Data Science Cookbook (n)

By : Yu-Wei, Chiu (David Chiu)
Book Image

R for Data Science Cookbook (n)

By: Yu-Wei, Chiu (David Chiu)

Overview of this book

This cookbook offers a range of data analysis samples in simple and straightforward R code, providing step-by-step resources and time-saving methods to help you solve data problems efficiently. The first section deals with how to create R functions to avoid the unnecessary duplication of code. You will learn how to prepare, process, and perform sophisticated ETL for heterogeneous data sources with R packages. An example of data manipulation is provided, illustrating how to use the “dplyr” and “data.table” packages to efficiently process larger data structures. We also focus on “ggplot2” and show you how to create advanced figures for data exploration. In addition, you will learn how to build an interactive report using the “ggvis” package. Later chapters offer insight into time series analysis on financial data, while there is detailed information on the hot topic of machine learning, including data classification, regression, clustering, association rule mining, and dimension reduction. By the end of this book, you will understand how to resolve issues and will be able to comfortably offer solutions to problems encountered while performing data analysis.
Table of Contents (19 chapters)
R for Data Science Cookbook
About the Author
About the Reviewer

Scraping web data

In most cases, the majority of data will not exist in your database, but will instead be published in different forms on the Internet. To dig up more valuable information from these data sources, we need to know how to access and scrape data from the Web. Here, we will illustrate how to use the rvest package to harvest finance data from

Getting ready

In this recipe, you need to prepare your environment with R installed and a computer that can access the Internet.

How to do it…

Perform the following steps to scrape data from

  1. First, access the following link to browse the S&P 500 index on the Bloomberg Business website

    Figure 9: S&P 500 index

  2. Once the page appears, as shown in the preceding screenshot, we can begin installing and loading the rvest package:

    >  install.packages("rvest")
    >  library(rvest)
  3. Next, you can use the HTML function from the rvest package to scrape and...