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R's strength comes from the community that has developed around the language and the packages that have been created and made available by the ones in the community. There are currently over 4,000 packages and libraries that you can import and utilize to make your data analysis tasks much easier.

Dr. Hadley Wickham is a notable member of the R community and he has produced a large number of highly regarded and often-used R packages. In this chapter you will primarily use two of his biggest hits, plyr and ggplot2 and a third package called reshape2. The package plyr will be used to apply the split-apply-combine data analysis pattern, explained later in this chapter, to our dataset and ggplot2 will make complex data visualizations significantly easier.