Book Image

Machine Learning with R Cookbook, Second Edition - Second Edition

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

Machine Learning with R Cookbook, Second Edition - Second Edition

By: Yu-Wei, Chiu (David Chiu)

Overview of this book

Big data has become a popular buzzword across many industries. An increasing number of people have been exposed to the term and are looking at how to leverage big data in their own businesses, to improve sales and profitability. However, collecting, aggregating, and visualizing data is just one part of the equation. Being able to extract useful information from data is another task, and a much more challenging one. Machine Learning with R Cookbook, Second Edition uses a practical approach to teach you how to perform machine learning with R. Each chapter is divided into several simple recipes. Through the step-by-step instructions provided in each recipe, you will be able to construct a predictive model by using a variety of machine learning packages. In this book, you will first learn to set up the R environment and use simple R commands to explore data. The next topic covers how to perform statistical analysis with machine learning analysis and assess created models, covered in detail later on in the book. You'll also learn how to integrate R and Hadoop to create a big data analysis platform. The detailed illustrations provide all the information required to start applying machine learning to individual projects. With Machine Learning with R Cookbook, machine learning has never been easier.
Table of Contents (21 chapters)
Title Page
Credits
About the Authors
About the Reviewers
www.PacktPub.com
Customer Feedback
Preface

Getting a dataset for machine learning


While R has a built-in dataset, the sample size and field of application is limited. Apart from generating data within a simulation, another approach is to obtain data from external data repositories. A famous data repository is the UCI machine learning repository, which contains both artificial and real datasets. This recipe introduces how to get a sample dataset from the UCI machine learning repository.

Getting ready

Ensure that you have completed the previous recipes by installing R on your operating system.

How to do it...

Perform the following steps to retrieve data for machine learning:

  1. Access the UCI machine learning repository: http://archive.ics.uci.edu/ml/.
  2. Click on view all data sets. Here you will find a list of datasets containing field names, such as Name, Data Types, Default Task, Attribute Types, #Instances, #Attributes, and Year:
  3. Use Ctrl + F to search for Iris:
  4. Click on Iris. This will display the data folder and the dataset description:
  5. Click on Data Folder, which will display a directory containing the iris dataset:
  1. You can then either download iris.data or use the read.csv function to read the dataset:
        > iris.data = read.csv(url("http://archive.ics.uci.edu/ml/machine-
        learning-databases/iris/iris.data"), header = FALSE,  col.names =
        c("Sepal.Length", "Sepal.Width", "Petal.Length", "Petal.Width", 
        "Species"))
        > head(iris.data)
        Output:
        Sepal.Length Sepal.Width Petal.Length Petal.Width   Species
        1         5.1         3.5          1.4         0.2 Iris-setosa
        2         4.9         3.0          1.4         0.2 Iris-setosa
        3         4.7         3.2          1.3         0.2 Iris-setosa
        4         4.6         3.1          1.5         0.2 Iris-setosa
        5         5.0         3.6          1.4         0.2 Iris-setosa
        6         5.4         3.9          1.7         0.4 Iris-setosa  

How it works...

Before conducting data analysis, it is important to collect your dataset. However, to collect an appropriate dataset for further exploration and analysis is not easy. We can, therefore, use the prepared dataset with the UCI repository as our data source. Here, we first access the UCI dataset repository and then use the iris dataset as an example. We can find the iris dataset by using the browser's find function (Ctrl + F), and then enter the file directory. Last, we can download the dataset and use the R I/O function, read.csv, to load the iris dataset into an R session.

See also