R/calcA.R

In nprcgenekeepr: Genetic Tools for Colony Management

#' Calculates \code{a}, the number of an individual's alleles that are rare in
#' each simulation.
## Copyright(c) 2017-2024 R. Mark Sharp
## This file is part of nprcgenekeepr
#'
#' Part of Genetic Value Analysis
#'
#' @return A matrix with named rows indicating the number of unique alleles
#'   an animal had during each round of simulation (indicated in columns).
#'
#' @param alleles a matrix with \{id, parent, V1 ... Vn\} providing the alleles
#' an animal received during each simulation.
#' The first 2 columns provide the animal ID and the parent the allele came
#' from. Remaining columns provide alleles.
#' @param threshold an integer indicating the maximum number of copies of an
#'  allele that can be present in the population for it to be considered rare.
#'  Default is 1.
#' @param byID logical variable of length 1 that is passed through to
#' eventually be used by \code{alleleFreq()}, which calculates the count of each
#'  allele in the provided vector. If \code{byID} is TRUE and ids are provided,
#'  the function will only count the unique alleles for an individual
#'   (homozygous alleles will be counted as 1).
#' @export
#' @examples
#' library(nprcgenekeepr)
#' rare <- calcA(nprcgenekeepr::ped1Alleles, threshold = 3, byID = FALSE)
calcA <- function(alleles, threshold = 1L, byID = FALSE) {
  ids <- alleles$id
  alleles <- alleles[, !(names(alleles) %in% c("id", "parent"))]

  countRare <- function(a) {
    if (byID) {
      f <- alleleFreq(a, ids)
    } else {
      f <- alleleFreq(a)
    }
    rareAlleles <- f$allele[f$freq <= threshold]
    a <- (a %in% rareAlleles)
    tapply(a, ids, sum)
  }

  return(apply(alleles, 2L, countRare))
}