R/get_summary.R

In visR: Clinical Graphs and Tables Adhering to Graphical Principles

#' @title Summarize the descriptive statistics across strata from a survival object using S3 method
#'
#' @description S3 method for extracting descriptive statistics across strata.
#'     No default method is available at the moment.
#'
#' @param x An object of class `survfit`
#' @param statlist Character vector containing the desired information to be displayed. The order of the arguments determines the order in which
#'    they are displayed in the final result. Default is the strata ("strata"), number of subjects ("records"), number of events ("events"),
#'    the median survival time ("median"), the Confidence Interval ("CI"), the Lower Confidence Limit ("UCL") and the Upper Confidence Limit ("UCL").
#' @param ... other arguments passed on to the method
#'
#' @return list of summary statistics from survfit object
#'
#' @rdname get_summary
#' @export
#'
get_summary <- function(x, ...) {
  UseMethod("get_summary", x)
}

#' @examples
#'
#' survfit_object <- survival::survfit(data = adtte, survival::Surv(AVAL, 1 - CNSR) ~ TRTP)
#' get_summary(survfit_object)
#'
#' @return A data frame with summary measures from a `survfit` object
#'
#' @rdname get_summary
#' @method get_summary survfit
#' @export
#'
get_summary.survfit <- function(x,
                                statlist = c("strata", "records", "events", "median", "LCL", "UCL", "CI"),
                                ...) {

  # User input validation ---------------------------------------------------

  statlist <- unique(statlist)

  if (is.null(statlist) |
    !base::all(statlist %in% c("strata", "records", "events", "median", "LCL", "UCL", "CI"))) {
    stop("Error in get_summary: Specify valid `statlist` arguments. Valid `statistic` arguments are:
    `strata`, `records`, `events`, `median`, `LCL`, `UCL` and `CI`. ")
  }

  # Adjust CI based on conf.int in survfit ----------------------------------


  if ("conf.int" %in% names(x) &
    x[["conf.type"]] != "none" &
    ((base::any(grepl("CL", statlist, fixed = TRUE))) | (base::any(grepl("CI", statlist, fixed = TRUE))))
  ) {
    CI <- paste0(x[["conf.int"]], statlist[grepl("CL", statlist, fixed = TRUE)])
    statlist[grepl("CL", statlist, fixed = TRUE)] <- CI

    CI_Varname <- paste0(x[["conf.int"]], statlist[grepl("CI", statlist, fixed = TRUE)])
    statlist[grepl("CI", statlist, fixed = TRUE)] <- CI_Varname
  } else if (!"conf.int" %in% names(x) | x[["conf.type"]] == "none") {
    statlist <- statlist[-which(grepl("CL", statlist, fixed = TRUE))]
    statlist <- statlist[-which(grepl("CI", statlist, fixed = TRUE))]

    warning("No conf.int estimated in x.")
  } else if (!base::any(statlist %in% c("LCL", "UCL", "CI"))) {
    CI_Varname <- "conf.in"
  }


  # Summary list ------------------------------------------------------------

  if ("strata" %in% names(x)) {
    strata <- names(x[["strata"]])
  } else {
    strata <- "Overall"
  }

  .CIpaste <- function(df) {
    if (base::any(grepl("CI", statlist, fixed = TRUE))) {
      paste0("(", apply(dplyr::select(df, matches(CI)), 1, paste, collapse = ";"), ")")
    } else {
      NULL
    }
  }

  summary_survfit <-
    as.data.frame(
      base::rbind(summary(x)[["table"]]),
      check.names = FALSE,
      stringsAsFactors = FALSE,
      row.names = NULL
    ) %>%
    dplyr::mutate(strata = strata) %>%
    dplyr::mutate(!!CI_Varname := .CIpaste(.)) %>%
    dplyr::select(dplyr::all_of(statlist))


  # Output to dataframe -----------------------------------------------------

  statlist <- base::sub("records", "No. of subjects", statlist, fixed = TRUE)
  statlist <- base::sub("events", "No. of events", statlist, fixed = TRUE)
  statlist <- base::sub("median", "Median(surv.time)", statlist, fixed = TRUE)

  colnames(summary_survfit) <- statlist

  return(summary_survfit)
}