R For Dummies

Andrie de Vries, Joris Meys

• Editore: For Dummies
• Anno: 2015
• ISBN:
  9781119055839
• Edizione: 2
• Argomento: Ciencia de la computación
• Categoria: Programación

Mastering R has never been easier

Picking up R can be tough, even for seasoned statisticians and data analysts. R For Dummies, 2 nd Edition provides a quick and painless way to master all the R you'll ever need. Requiring no prior programming experience and packed with tons of practical examples, step-by-step exercises, and sample code, this friendly and accessible guide shows you how to know your way around lists, data frames, and other R data structures, while learning to interact with other programs, such as Microsoft Excel. You'll learn how to reshape and manipulate data, merge data sets, split and combine data, perform calculations on vectors and arrays, and so much more.

R is an open source statistical environment and programming language that has become very popular in varied fields for the management and analysis of data. R provides a wide array of statistical and graphical techniques, and has become the standard among statisticians for software development and data analysis. R For Dummies, 2 nd Edition takes the intimidation out of working with R and arms you with the knowledge and know-how to master the programming language of choice among statisticians and data analysts worldwide.

• Covers downloading, installing, and configuring R
• Includes tips for getting data in and out of R
• Offers advice on fitting regression models and ANOVA
• Provides helpful hints for working with graphics

R For Dummies, 2 nd Edition is an ideal introduction to R for complete beginners, as well as an excellent technical reference for experienced R programmers.

Part I

Getting Started with R Programming

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In this part …

Introducing R programming concepts.

Creating your first script.

Making clear, legible code.

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Chapter 1

Introducing R: The Big Picture

In This Chapter

Discovering the benefits of R

Identifying some programming concepts that make R special

With an estimated worldwide user base of more than 2 million people, the R language has rapidly grown and extended since its origin as an academic demonstration language in the 1990s.

Some people would argue — and we think they’re right — that R is much more than a statistical programming language. It’s also

• A very powerful tool for all kinds of data processing and manipulation
• A community of programmers, users, academics, and practitioners
• A tool that makes all kinds of publication-quality graphics and data visualizations
• A collection of freely distributed add-on packages
• A versatile toolbox for extensive automation of your work

In this chapter, we fill you in on the benefits of R, as well as its unique features and quirks.

You can download R at www.r-project.org. This website also provides more information on R and links to the online manuals, mailing lists, conferences, and publications.

Tracing the history of R

Ross Ihaka and Robert Gentleman developed R as a free software environment for their teaching classes when they were colleagues at the University of Auckland in New Zealand. Because they were both familiar with S, a programming language for statistics, it seemed natural to use similar syntax in their own work. After Ihaka and Gentleman announced their software on the S-news mailing list, several people became interested and started to collaborate with them, notably Martin Mächler.

Currently, a group of 21 people has rights to modify the central archive of source code (http://www.r-project.org/contributors.html). This group is referred to as the R Core Team. In addition, many other people have contributed new code and bug fixes to the project.

Here are some milestone dates in the development of R:

• Early 1990s: The development of R began.
• August 1993: The software was announced on the S-news mailing list. Since then, a set of active R mailing lists has been created. The web page at www.r-project.org/mail.html provides descriptions of these lists and instructions for subscribing. (For more information, turn to “It provides an engaged community,” later in this chapter.)
• June 1995: After some persuasive arguments by Martin Mächler (among others) to make the code available as “free software,” the code was made available under the Free Software Foundation’s GNU General Public License (GPL), Version 2.
• Mid-1997: The initial R Development Core Team was formed (although, at the time, it was simply known as the core group).
• February 2000: The first version of R, version 1.0.0, was released.
• October 2004: Release of R version 2.0.0.
• April 2013: Release of R version 3.0.0.
• April 2015: Release of R-3.2.0 (the version used in this book).

Ross Ihaka wrote a comprehensive overview of the development of R. The web page http://cran.r-project.org/doc/html/interface98-paper/paper.html provides a fascinating history.

Recognizing the Benefits of Using R

Of the many attractive benefits of R, a few stand out: It’s actively maintained, it has good connectivity to various types of data and other systems, and it’s versatile enough to solve problems in many domains. Possibly best of all, it’s available for free, in more than one sense of the word.

It comes as free, open-source code

R is available under an open-source license, which means that anyone can download and modify the code. This freedom is often referred to as “free as in speech.” R is also available free of charge — a second kind of freedom, sometimes referred to as “free as in beer.” In practical terms, this means that you can download and use R free of charge.

As a result of this freedom, many excellent programmers have contributed improvements and fixes to the R code. For this reason, R is very stable and reliable.

Any freedom also has associated obligations. In the case of R, these obligations are described in the conditions of the license under which it is released: GNU General Public License (GPL), Version 2. The full text of the license is available at www.r-project.org/COPYING. It’s important to stress that the GPL does not pertain to your usage of R. There are no obligations for using the software — the obligations just apply to redistribution. In short, if you change and redistribute the R source code, you have to make those changes available for anybody else to use.

It runs anywhere

The R Core Team has put a lot of effort into making R available for different types of hardware and software. This means that R is available for Windows, Unix systems (such as Li...