Chapter 13

Manipulating and Processing Data

In This Chapter

arrow Creating subsets of data

arrow Adding calculated fields

arrow Merging data from different sources

arrow Sorting data

arrow Meeting more members of the apply family

arrow Getting your data into shape

Now it’s time to put together all the tools that you encounter 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 get to 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 get to use some techniques for reshaping data — for example, changing the shape of data from wide format to long format.

Deciding on the Most Appropriate Data Structure

The first ...

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