10  Grouped operations

Learning objectives

10.1 Context

We’ve done different types of operations, all on the entire data set. Sometimes there is structure within the data, such as different groups (e.g. genotypes, patient cohorts, geographical areas etc). We might then want information on a group-by-group basis.

10.2 Summary operations

10.2.1 Summarising data

LO: summarising data

10.2.2 Grouped summaries

LO: grouped summaries

10.3 Counting data

10.3.1 Counting

LO: counting

10.3.2 Counting by group

LO: counting data by group

10.3.3 Counting missing values

LO: counting with missing values

10.4 Grouped operations

10.4.1 Grouped filters

LO: grouped filters

10.4.2 Grouped changes

LO: grouped mutate

10.4.3 To ungroup or not ungroup

LO: the importance of ungrouping

10.5 Summary

Key points