Beyond Spreadsheets with R

6 Selecting data values

This chapter covers

• Manipulating strings
• Selecting groups of values from different structures
• Conditionally selecting values
• Replacing certain values
• Manipulating data.frames in a better way: dplyr

Now that you’ve learned how to group values together into larger structures, it’s going to be useful to access smaller components of those from time to time, be it a column from a data.frame, a row from a matrix, or part of a string. Extracting data from larger structures is both one of the most common and most dangerous (because of various R quirks) operations that you’ll perform with the language. Knowing what the dangers are and to expect them rather than be surprised by them is a defensive strategy, and there’s value ...