======areaplot======
This is an R plot that was submitted to R-devel by Arni Magnusson.
<code rsplus areaplot.R>
areaplot <-
function(x, ...)
{
  UseMethod("areaplot")
}

areaplot.default <-
function(x, y=NULL, prop=FALSE, add=FALSE, xlab=NULL, ylab=NULL, col=NULL, ...)
{
  if(is.ts(x)) # ts/mts
  {
    if(is.null(ylab))
      ylab <- deparse(substitute(x))
    x <- data.frame(Time=time(x), x)
  }
  if(is.table(x))  # table
  {
    if(is.null(ylab))
      ylab <- deparse(substitute(x))
    if(length(dim(x)) == 1)
      x <- t(t(unclass(x)))
    else
      x <- unclass(x)
  }
  if(is.matrix(x))  # matrix
  {
    if(!is.null(rownames(x)) && !any(is.na(suppressWarnings(as.numeric(rownames(x))))))
    {
      x <- data.frame(as.numeric(rownames(x)), x)
      names(x)[1] <- ""
    }
    else
    {
      x <- data.frame(Index=seq_len(nrow(x)), x)
    }
  }
  if(is.list(x))  # data.frame or list
  {
    if(is.null(xlab))
      xlab <- names(x)[1]
    if(is.null(ylab))
    {
      if(length(x) == 2)
        ylab <- names(x)[2]
      else
        ylab <- ""
    }
    y <- x[-1]
    x <- x[[1]]
  }
  if(is.null(y))  # one numeric vector passed, plot it on 1:n
  {
    if(is.null(xlab))
      xlab <- "Index"
    if(is.null(ylab))
      ylab <- deparse(substitute(x))
    y <- x
    x <- seq_along(x)
  }
  if(is.null(xlab))
    xlab <- deparse(substitute(x))
  if(is.null(ylab))
    ylab <- deparse(substitute(y))

  y <- as.matrix(y)
  if(is.null(col))
    col <- gray.colors(ncol(y))
  col <- rep(col, length.out=ncol(y))
  if(prop)
    y <- prop.table(y, 1)
  y <- t(rbind(0, apply(y, 1, cumsum)))
  na <- is.na(x) | apply(is.na(y),1,any)
  x <- x[!na][order(x[!na])]
  y <- y[!na,][order(x[!na]),]

  if(!add)
    suppressWarnings(matplot(x, y, type="n", xlab=xlab, ylab=ylab, ...))
  xx <- c(x, rev(x))
  for(i in 1:(ncol(y)-1))
  {
    yy <- c(y[,i+1], rev(y[,i]))
    suppressWarnings(polygon(xx, yy, col=col[i], ...))
  }

  invisible(y[,-1])
}

areaplot.formula <-
function (formula, data, subset, na.action=NULL, ...)
{
  m <- match.call(expand.dots=FALSE)
  if(is.matrix(eval(m$data,parent.frame())))
    m$data <- as.data.frame(data)
  m$... <- NULL
  m[[1]] <- as.name("model.frame")
  if(as.character(formula[[2]]=="."))
  {
    rhs <- unlist(strsplit(deparse(formula[[3]])," *[:+] *"))
    lhs <- sprintf("cbind(%s)", paste(setdiff(names(data),rhs),collapse=","))
    m[[2]][[2]] <- parse(text=lhs)[[1]]
  }

  mf <- eval(m, parent.frame())
  if(is.matrix(mf[[1]]))
  {
    lhs <- as.data.frame(mf[[1]])
    names(lhs) <- as.character(m[[2]][[2]])[-1]
    areaplot.default(cbind(mf[-1],lhs), ...)
  }
  else
  {
    areaplot.default(mf[2:1], ...)
  }
}
</code>

<code rsplus areaplot.Rd>
\name{areaplot}
\alias{areaplot}
\alias{areaplot.default}
\alias{areaplot.formula}
\title{Area Plots}
\description{
  Produce a stacked area plot, or add polygons to an existing plot.
}
\usage{
areaplot(x, \dots)

\method{areaplot}{default}(x, y = NULL, prop = FALSE, add = FALSE, xlab = NULL,
         ylab = NULL, col = NULL, \dots)

\method{areaplot}{formula}(formula, data, subset, na.action = NULL, \dots)
}
\arguments{
  \item{x}{numeric vector of x values, or if \code{y=NULL} a numeric
    vector of y values. Can also be a 1-dimensional table (x values in
    names, y values in array), matrix or 2-dimensional table (x values
    in row names and y values in columns), a data frame (x values in
    first column and y values in subsequent columns), or a time-series
    object of class \code{ts/mts}.}
  \item{y}{numeric vector of y values, or a matrix containing y values
    in columns.}
  \item{prop}{whether data should be plotted as proportions, so stacked
    areas equal 1.}
  \item{add}{whether polygons should be added to an existing plot.}
  \item{xlab}{label for x axis.}
  \item{ylab}{label for y axis.}
  \item{col}{fill color of polygon(s). The default is a vector of gray
    colors.}
  \item{formula}{a \code{\link{formula}}, such as \code{y ~ x} or
    \code{cbind(y1, y2) ~ x}, specifying x and y values. A dot on the
    left-hand side, \code{formula = . ~ x}, means all variables except
    the one specified on the right-hand side.}
  \item{data}{a data frame (or list) from which the variables in
    \code{formula} should be taken.}
  \item{subset}{an optional vector specifying a subset of observations
    to be used.}
  \item{na.action}{a function which indicates what should happen when
    the data contain \code{NA} values. The default is to ignore missing
    values in the given variables.}
  \item{\dots}{further arguments passed to \code{matplot} and
    \code{polygon}.}
}
\value{
  Matrix of cumulative sums that was used for plotting.
}
\author{
  Arni Magnusson.
}
\seealso{
  \code{\link{barplot}}, \code{\link{polygon}}.
}
\examples{
areaplot(rpois(10,40))
areaplot(rnorm(10))

# formula
areaplot(Armed.Forces~Year, data=longley)
areaplot(cbind(Armed.Forces,Unemployed)~Year, data=longley)

# add=TRUE
plot(1940:1970, 500*runif(31), ylim=c(0,500))
areaplot(Armed.Forces~Year, data=longley, add=TRUE)

# matrix
areaplot(WorldPhones)
areaplot(WorldPhones, prop=TRUE)

# table
require(MASS)
areaplot(table(Aids2$age))
areaplot(table(Aids2$age, Aids2$sex))

# ts/mts
areaplot(austres)
areaplot(Seatbelts[,c("drivers","front","rear")],
         ylab="Killed or seriously injured")
abline(v=1983+1/12, lty=3)
}
</code>