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Compact group indices

Source: R/groups.R
compact_groups.Rd

Given a vector of group indices (where 0 means no group), compacts the indices so they are in the range 1 to N, where N is the number of unique groups.

Usage

compact_groups(group_indices)

Arguments

group_indices

An integer vector where element i contains the group index for entry i. A value of 0 indicates the entry belongs to no group.

Value

A list with two elements:

  • n_groups: The number of unique groups (N)

  • group_indices: The compacted group indices (in range 1..N, with 0 unchanged)

Details

This function is useful when group indices have gaps (e.g., groups 5 and 10) and need to be renumbered to consecutive integers (1 and 2).

Examples

if (FALSE) { # \dontrun{
# Groups 5 and 10 with gaps
group_indices <- c(5L, 10L, 5L, 0L, 10L)
result <- compact_groups(group_indices)
# result$n_groups is 2
# result$group_indices is c(1L, 2L, 1L, 0L, 2L)
} # }