Conventions

In this book, you will find a number of styles of text that distinguish between different kinds of information. Here are some examples of these styles, and an explanation of their meaning.

Package and function names are shown as follows: "You can then install and load the package RCurl."

A block of code is set as follows:

> install.packages("RCurl")
> library(RCurl)

Any URL is written as follows:

http://data.worldbank.org/topic/economy-and-growth

Variable name, argument name, new terms and important words are shown in bold. Words that you see on the screen, in menus or dialog boxes for example, appear in the text like this: "In R, a missing value is noted with the symbol NA (not available), and an impossible value is NaN (not a number)."