R/splits.R

In redist: Simulation Methods for Legislative Redistricting

#' Count County Splits
#' @param plans A numeric vector (if only one map) or matrix with one row
#' for each precinct and one column for each map. Required.
#' @param counties A vector of county names or county ids.
#'
#' @return integer vector with one number for each map
#'
#' @concept analyze
#' @export
redist.splits <- function(plans, counties) {
    if (missing(plans)) {
        cli_abort("Please provide an argument to {.arg plans}.")
    }
    if (inherits(plans, "redist_plans")) {
        plans <- get_plans_matrix(plans)
    }
    if (!is.matrix(plans)) {
        plans <- matrix(plans, ncol = 1)
    }
    if (any(class(plans) %in% c("numeric", "matrix"))) {
        plans <- redist.reorder(plans)
    }

    if (missing(counties)) {
        cli_abort("Please provide an argument to {.arg counties}.")
    }


    redistmetrics::splits_admin(plans = plans, shp = data.frame(),
        admin = counties)
}

#' Identify which counties are split by a plan
#'
#' @param plan A vector of precinct/unit assignments
#' @param counties A vector of county names or county ids.
#'
#' @return A logical vector which is \code{TRUE} for precincts belonging to
#' counties which are split
#'
#' @concept analyze
#' @export
is_county_split <- function(plan, counties) {
    counties <- as.integer(as.factor(counties))
    as.logical((tapply(plan, counties, FUN = function(y) length(unique(y))) > 1)[counties])
}


#' Counts the Number of Counties within a District
#'
#' Counts the total number of counties that are found within a district.
#' This does not subtract out the number of counties that are found completely
#' within a district.
#'
#' @param plans A numeric vector (if only one map) or matrix with one row
#' for each precinct and one column for each map. Required.
#' @param counties A vector of county names or county ids.
#'
#' @return integer matrix where each district is a
#'
#' @concept analyze
#' @export
#'
#' @examples
#' data(iowa)
#' ia <- redist_map(iowa, existing_plan = cd_2010, total_pop = pop, pop_tol = 0.01)
#' plans <- redist_smc(ia, 50, silent = TRUE)
#' splits <- redist.district.splits(plans, ia$region)
redist.district.splits <- function(plans, counties) {
    if (missing(plans)) {
        stop("Please provide an argument to plans.")
    }
    if (inherits(plans, "redist_plans")) {
        plans <- get_plans_matrix(plans)
    }
    if (!is.matrix(plans)) {
        plans <- matrix(plans, ncol = 1)
    }
    if (!any(class(plans) %in% c("numeric", "matrix"))) {
        stop('Please provide "plans" as a matrix.')
    }

    if (missing(counties)) {
        stop("Please provide an argument to counties.")
    }
    if (class(counties) %in% c("character", "numeric", "integer")) {
        county_id <- redist.county.id(counties)
    } else {
        stop('Please provide "counties" as a character, numeric, or integer vector.')
    }


    dist_cty_splits(plans - 1, community = county_id - 1, length(unique(plans[, 1])))
}


#' Counts the Number of Counties Split Between 3 or More Districts
#'
#' Counts the total number of counties that are split across more than 2 districts.
#'
#' @param plans A numeric vector (if only one map) or matrix with one row
#' for each precinct and one column for each map. Required.
#' @param counties A vector of county names or county ids.
#'
#' @return integer matrix where each district is a
#'
#' @concept analyze
#' @export
#'
#' @examples
#' data(iowa)
#' ia <- redist_map(iowa, existing_plan = cd_2010, total_pop = pop, pop_tol = 0.01)
#' plans <- redist_smc(ia, 50, silent = TRUE)
#' splits <- redist.multisplits(plans, ia$region)
redist.multisplits <- function(plans, counties) {
    if (missing(plans)) {
        cli_abort("Please provide an argument to {.arg plans}.")
    }
    if (inherits(plans, "redist_plans")) {
        plans <- get_plans_matrix(plans)
    }
    if (!is.matrix(plans)) {
        plans <- matrix(plans, ncol = 1)
    }
    if (any(class(plans) %in% c("numeric", "matrix"))) {
        plans <- redist.reorder(plans)
    }

    if (missing(counties)) {
        cli_abort("Please provide an argument to {.arg counties}.")
    }

    redistmetrics::splits_multi(plans = plans, shp = data.frame(),
        admin = counties)
}


#' Counts the Number of Municipalities Split Between Districts
#'
#' Counts the total number of municpalities that are split.
#' Municipalities in this interpretation do not need to cover the entire state, which
#' differs from counties.
#'
#' @param plans A numeric vector (if only one map) or matrix with one row
#' for each precinct and one column for each map. Required.
#' @param munis A vector of municipality names or ids.
#'
#' @return integer vector of length ndist by ncol(plans)
#'
#' @concept analyze
#' @export
#'
#' @examples
#' data(iowa)
#' ia <- redist_map(iowa, existing_plan = cd_2010, total_pop = pop, pop_tol = 0.01)
#' plans <- redist_smc(ia, 50, silent = TRUE)
#' ia$region[1:10] <- NA
#' splits <- redist.muni.splits(plans, ia$region)
redist.muni.splits <- function(plans, munis) {
    redistmetrics::splits_sub_admin(plans = plans, shp = data.frame(),
        sub_admin = munis)
}

#' @rdname redist.muni.splits
#' @order 1
#'
#' @param map a \code{\link{redist_map}} object
#' @param .data a \code{\link{redist_plans}} object
#'
#' @concept analyze
#' @export
muni_splits <- function(map, munis, .data = cur_plans()) {
    check_tidy_types(map, .data)
    idxs <- unique(as.integer(.data$draw))
    munis <- rlang::eval_tidy(rlang::enquo(munis), map)
    redist.muni.splits(plans = get_plans_matrix(.data)[, idxs, drop = FALSE], munis = munis)
}