Assign a group to each row of a data.table

Assign a group to each row of a data.table. If by is specified, then each unique combination of the columns in by will be assigned a unique group. If by is not specified, then all rows will be assigned to the same group.

Usage

enw_assign_group(obs, by = NULL, copy = TRUE)

Arguments

obs

A data.table or data.frame without a .group column.

by

A character vector of column names to group by. Defaults to an empty vector.

copy

A logical; make a copy (default) of obs or modify it in place?

Value

A data.table with a .group column added ordered by .group

and the existing key of obs.

See also

Preprocessing functions enw_add_delay(), enw_add_max_reported(), enw_add_metaobs_features(), enw_complete_dates(), enw_construct_data(), enw_extend_date(), enw_filter_delay(), enw_filter_reference_dates(), enw_filter_report_dates(), enw_flag_observed_observations(), enw_impute_na_observations(), enw_latest_data(), enw_metadata_delay(), enw_metadata(), enw_missing_reference(), enw_preprocess_data(), enw_reporting_triangle_to_long(), enw_reporting_triangle()

Examples

obs <- data.frame(x = 1:3, y = 1:3)
enw_assign_group(obs)
#> Key: <.group>
#>        x     y .group
#>    <int> <int>  <num>
#> 1:     1     1      1
#> 2:     2     2      1
#> 3:     3     3      1
enw_assign_group(obs, by = "x")
#> Key: <.group>
#>        x     y .group
#>    <int> <int>  <int>
#> 1:     1     1      1
#> 2:     2     2      2
#> 3:     3     3      3