R/rep_sample_n.R

In statsr: Companion Software for the Coursera Statistics with R Specialization

#' Repeating Sampling from a Tibble
#' 
#' @param tbl tbl of data.
#' @param size The number of rows to select.
#' @param replace Sample with or without replacement?
#' @param reps The number of samples to collect.
#' @return A tbl_df that aggregates all created samples, with the addition of a \code{replicate} column that the tbl_df is also grouped by
#' @examples 
#' data(nc)
#' rep_sample_n(nc, size=10, replace=FALSE, reps=1)
#' @export

rep_sample_n <- function(tbl, size, replace = FALSE, reps = 1)
{
    n <- nrow(tbl)
    i <- unlist(replicate(reps, sample.int(n, size, replace = replace), simplify = FALSE))

    rep_tbl <- cbind(replicate = rep(1:reps,rep(size,reps)), tbl[i, , drop=FALSE])

    dplyr::group_by(rep_tbl, replicate)
}