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Data Mashups in R by Xiao-Yi Li, Jeremy Leipzig

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Appendix A. Getting Started

Obtaining R

R is available here: http://cran.r-project.org/.

Consoles with a limited but handy menu come with the Windows and Mac distributions. These make it somewhat easier to browse available packages and documentation. In Unix, the R executable will generally install into /usr/bin/R and uses the X Window System (X11) for graphs.

The commands in this book work for all R platforms.

Quick and Dirty Essentials of R

Upon starting R, you will see a prompt describing the version of R you are accessing, a disclaimer about R as a free software, and some functions regarding license, contributors, and demos of R.

R uses an interactive shell—each line is interpreted after you hit return. A > prompt appears when R is ready for another command. In this book, all commands that a user enters appear in bold after the prompt.

Built-in functions and simple mathematical calculations are the basics of R language. By typing 1+1 and hitting Enter, you’ll observe the following:

  > 1+1 
  [1] 2  

  > myAnswer<-sqrt(81)
  > myAnswer
   [1] 9 

Just like a calculator, you can also take logs with log(), find the sin of angles with sin(), and take absolute values of any real number with abs(). R allows you to store your results in a variable by using the <- operator. To view the value of a variable, simply type its name. Names in R are case-sensitive, so one, One, and oNe are three different variables. You can also create a vector (a collection of elements) using variables of the same type (int ...

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