R/bootSlope.formula.R

In CarletonStats: Functions for Statistics Classes at Carleton College

#' @describeIn bootSlope Bootstrap the slope of a simple linear regression line
#' @export

bootSlope.formula <-
  function(formula,  data, subset,  ...)
  {
    
    if (missing(formula) || (length(formula) != 3L) || (length(attr(terms(formula[-2L]),
                                                                    "term.labels")) != 1L))
      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())
    if (length(mf)!= 2L)
      stop("Invalid formula")
    
    nmiss <- length(attr(mf, "na.action"))
    if (nmiss > 0)
      cat("\n ", nmiss, "observation(s) removed due to missing values.\n")
    varnames <- names(mf)
    response <- attr(attr(mf, "terms"), "response")
    y <- mf[[response]]
    x <- mf[[-response]]
    y <- do.call("bootSlope", list(x, y, x.name=varnames[2], y.name=varnames[1],...))
    
    y
  }