R/cut_data_by_date.R

In Merck/simtrial: Clinical Trial Simulation

#  Copyright (c) 2024 Merck & Co., Inc., Rahway, NJ, USA and its affiliates.
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#
#  This file is part of the simtrial program.
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#' Cut a dataset for analysis at a specified date
#'
#' @param x A time-to-event dataset, for example, generated by [sim_pw_surv()].
#' @param cut_date Date relative to start of randomization
#'   (`cte` from input dataset) at which dataset is to be cut off for analysis.
#'
#' @return A data frame ready for survival analysis, including columns time to
#'   event (`tte`), `event`, the `stratum`, and the `treatment`. The class of
#'   the data frame is `tte_data`, and the attribute `ratio` generated by
#'   [sim_pw_surv()] is also attached.
#'
#' @importFrom data.table ":=" as.data.table setDF
#'
#' @export
#'
#' @examples
#' # Use default enrollment and event rates and
#' # cut at calendar time 5 after start of randomization
#' sim_pw_surv(n = 20) |> cut_data_by_date(5)
cut_data_by_date <- function(x, cut_date) {
  ans <- as.data.table(x)
  ans <- ans[enroll_time <= cut_date, ]
  ans[, tte := pmin(cte, cut_date) - enroll_time]
  ans[, event := fail * (cte <= cut_date)]
  ans <- ans[, c("tte", "event", "stratum", "treatment")]

  setDF(ans)

  attr(ans, "ratio") <- attributes(x)$ratio

  class(ans) <- c("tte_data", class(ans))
  return(ans)
}