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Group a cohort's subjects by one or more columns

Source: R/groups.R
cohort_groups.Rd

Groups cohort@subject_tbl by the given columns and returns one row per combination that actually occurs, with the matching subject ids.

Usage

cohort_groups(cohort, by)

Arguments

cohort

A Cohort object.

by

Character vector of one or more subject_tbl column names to group by. Required, no default.

Value

A tibble with the by columns, group_label (the by values pasted together with "/"), n (the number of subjects), and subject_ids (a list-column of sorted, unique subject ids).

Details

Only combinations that occur in subject_tbl appear; this never invents a row for a combination of values that no subject has. An NA in a by column forms its own group rather than being dropped.

See also

cohort_contrasts(), subjects()

Examples

data(example_cohort)
cohort_groups(example_cohort, by = "species")
#> # A tibble: 2 × 4
#>   species group_label     n subject_ids
#>   <chr>   <chr>       <int> <list>     
#> 1 mouse   mouse           2 <chr [2]>  
#> 2 rat     rat             2 <chr [2]>