8.3 Summary

ds4psy: (8) Joining data

This chapter showed us various ways of combining 2 tables by using the 2-table verbs of the dplyr package [R-dplyr]. Depending on the type of combination we wanted to achieve, we used various join commands or set operations.

After working through this chapter, you should be able to use 2-table verbs of dplyr to:

  1. perform various mutating joins on 2 tables;
  2. perform various filtering joins on 2 tables;
  3. combine the cases of 2 tables with set operations; and
  4. know that base::merge also allows performing mutating joins.

The same procedure can be applied repeatedly to generalize beyond situations that only contain 2 tables. Take a look at Page 2 of the R Studio Cheat Sheet on Data transformation to check which commands you are now familiar with and which others you can still discover in the future:

Joining data with 2-table verbs of **dplyr**. 
(summary from [R Studio Cheat Sheets](https://www.rstudio.com/resources/cheatsheets/#dplyr)).

Figure 8.2: Joining data with 2-table verbs of dplyr. (summary from R Studio Cheat Sheets).

Let’s test our knowledge and skills on joining tables by completing the following exercises.