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Continuum of Care (CoC) merger crosswalk over time

Source: R/coc_mergers.R
coc_mergers.Rd

Records how HUD Continuum of Care (CoC) numbers were reassigned when CoCs merged. CoCs merge and are renumbered frequently, so a code that appears in an early year of the hud20XX / coc20XX series may have been absorbed into a different CoC later. Use this table to harmonize CoC codes across years – for example to follow a CoC's homeless counts through a merger, or to roll historical codes forward to the surviving CoC.

Usage

coc_mergers

Format

A data frame with one row per merger and 3 variables:

coc_pre

CoC number before the merger, e.g. "AR-502".

coc_post

Surviving CoC number after the merger, e.g. "AR-503".

merger_year

Year the merger took effect (integer).

Source

"CoC Mergers" sheet of HUD's PIT-by-CoC workbook (AHAR Part 1): https://www.huduser.gov/portal/datasets/ahar/2024-ahar-part-1-pit-estimates-of-homelessness-in-the-us.html

Examples

# Resolve any historical CoC code to its current (post-merger) code
resolve_coc <- function(code, mergers = coc_mergers) {
  repeat {
    hit <- mergers$coc_post[match(code, mergers$coc_pre)]
    if (is.na(hit) || hit == code) return(code)
    code <- hit
  }
}
resolve_coc("AR-502")  # -> "AR-503"
#> [1] "AR-503"