R/stemPlot.default.R

In CarletonStats: Functions for Statistics Classes at Carleton College

#' @describeIn stemPlot Stem and leaf plot
#' @export

stemPlot.default <-
function(x, grpvar = NULL, varname = NULL, grpvarname = NULL, ...)
{
    if (!is.numeric(x)) stop("variable must be numeric")

    if (is.null(varname))
       varname <- deparse(substitute(x))

    comCases <- complete.cases(x)
    nmiss <- length(x) - sum(comCases)
    if (nmiss > 0)
      cat("\n ", nmiss, "observation(s) removed due to missing values.\n")

     cat("\n***Stem and Leaf plot for ", varname, "***\n")

     if (!is.null(grpvar))
       {

         if (is.null(grpvarname))
          grpvarname <- deparse(substitute(grpvar))

         if (!is.factor(grpvar))
          {grpvar <- as.factor(grpvar)
          } else grpvar <- droplevels(grpvar)

         grp.levels <- levels(grpvar)

       cat("   Grouped by levels of ", grpvarname, "\n")
        for (i in grp.levels)
         {
          cat("\n   " ,i,"\n :")
          stem(x[grpvar == i],...)

         } #end for
         } else  { stem(x, ...)}


  invisible()
}