R/whichDdt.R

In nlmixr2lib: A Model Library for 'nlmixr2'

#' Figures out what line d/dt(central) is on
#'
#' @param modelLines modelLines expression list
#' @param central name of central compartment
#' @param start is the start of the expression, by default it is "d/dt("
#' @param end is the end of the expression, by default it is ")"
#' @return which item in modelLines is the central compartment (or
#'   error if there is multiple lines)
#' @noRd
#' @author Matthew L. Fidler
.whichDdt <- function(modelLines, central, start="d/dt(", end=")") {
  .dd1 <- start
  .dd2 <- end
  .ddtCentral1 <- str2lang(paste0(.dd1, central, .dd2, " <- ."))
  .ddtCentral2 <- str2lang(paste0(.dd1, central, .dd2, " = ."))
  .w <- which(vapply(seq_along(modelLines),
                     function(i) {
                       .cur <- modelLines[[i]]
                       rxode2::.matchesLangTemplate(.cur, .ddtCentral1) ||
                         rxode2::.matchesLangTemplate(.cur, .ddtCentral2)
                     }, logical(1), USE.NAMES = FALSE))
  # Modify ODE for central compartment
  if (length(.w) != 1) {
    stop("'",
         .dd1,
         central,
         .dd2,
         "' not found or duplicated in model",
         call.=FALSE)
  }
  .w
}