In This Chapter
Creating subsets of data
Adding calculated fields
Merging data from different sources
Meeting more members of the apply family
Getting your data into shape
Now it’s time to put together all the tools you've seen in earlier chapters. You know how to get data into R, you know how to work with lists and data frames, and you know how to write functions. Combined, these tools form the basic toolkit to be able to do data manipulation and processing in R.
In this chapter, you use some tricks and design idioms for working with data. This includes methods for selecting and ordering data, such as working with lookup tables. You also use some techniques for reshaping data — for example, changing the shape of data from wide format to long format.
The first decision you have ...