R/boot.formula.R

In CarletonStats: Functions for Statistics Classes at Carleton College

#' @describeIn boot Bootstrap a single variable or a grouped variable
#' @export

boot.formula <-
  function(formula,  data, subset, ...)
  {
    
    if (missing(formula) || (length(formula) > 3L) )
      stop("'formula' missing or incorrect")
    
    m <- match.call(expand.dots = FALSE)
    if (is.matrix(eval(m$data, parent.frame())))
      m$data <- as.data.frame(data)
    m[[1L]] <- as.name("model.frame")
    m$... <- NULL
    mf <- eval(m, parent.frame())
    
    nmiss <- length(attr(mf, "na.action"))
    if (nmiss > 0)
      cat("\n ", nmiss, "observation(s) removed due to missing values.\n")
    varnames <- names(mf)
    
    if (length(formula) == 2L){
      g <- NULL
      y <- mf[[1]]
      
    }
    else{
      response <- attr(attr(mf, "terms"), "response")
      y <- mf[[response]]
      g <- mf[[-response]]
      
    }
    
    y <- do.call("boot", c(list(y, g,  x.name=varnames[1]), list(...)))
    
    y
  }