\name{apc.lines}
\alias{apc.lines}
\title{
  Plot APC-estimates in an APC-frame.
}
\description{
  When an APC-frame has been produced by \code{\link{apc.frame}}, this
  function draws a set of estimates from an APC-fit in the frame. An
  optional drift parameter can be added to the period parameters and
  subtracted from the cohort- and age parameters.
}
\usage{
 apc.lines( A, P, C,
            scale = "log",
        frame.par = c(min(C[, 1]) + max(A[, 1]),
                      ifelse( scale == "log",
                              exp(mean(A[, 2])),
                              exp(mean(log(A[, 2]))))),
            drift = 0,
               c0 = median(C[, 1]),
               a0 = median(A[, 1]),
               p0 = c0 + a0,
               ci = rep(FALSE, 3),
              lwd = c(3, 1, 1),
              lty = rep(1, 3),
              col = rep("black", 3))
}
\arguments{
  \item{A}{Age effects. A 4-column matrix with columns age, age-specific
  rates, lower and upper c.i.}
  \item{P}{Period effects. Rate-ratios. Same form as for the age-effects.}
  \item{C}{Cohort effects. Rate-ratios. Same form as for the age-effects.}
  \item{scale}{Are effects given on a log-scale? Character variable, one
    of \code{"log"}, \code{"ln"}, \code{"rates"}, \code{"inc"},
    \code{"RR"}. If \code{"log"} or \code{"ln"} it is assumed that
    effects are log(rates) and log(RRs) otherwise the actual effects are
    assumed given in \code{A}, \code{P} and \code{C}.} 
  \item{frame.par}{2-element vector with the cohort-period offset, and
    RR multiplicator. This will typically be the result from the call of
    \code{\link{apc.frame}}} 
  \item{drift}{The drift parameter to be added to the period effect. If
    \code{scale="log"} this is assumed to be on the log-scale, otherwise
    it is assumed to be a multiplicative factor per unit of the first
    columns of  \code{A}, \code{P} and \code{C} } 
  \item{c0}{The cohort where the drift is assumed to be 0; the subtracted
  drift effect is \code{drift*(C[,1]-c0)}.}
  \item{a0}{The age where the drift is assumed to be 0.}
  \item{p0}{The period where the drift is assumed to be 0.}
  \item{ci}{Should confidence interval be drawn. Logical or
    character. If character, any occurrence of \code{"a"} or \code{"A"}
    produces confidence intervals for the age-effect. Similarly for
    period and cohort.}
  \item{lwd}{Line widths for estimates, lower and upper confidence limits.}
  \item{lty}{Linetypes for the three effects.}
  \item{col}{Colours for the three effects.}
}
\details{
  The drawing of three effects in an APC-frame is a rather trivial task,
  and the main purpose of the utility is to provide a function that
  easily adds the functionality of adding a drift so that several sets
  of lines can be easily produced in the same frame.
}
\value{
  A list of three matrices with the effects actually plotted is
  returned invisibly.
}
\references{}
\author{
  Bendix Carstensen, Steno Diabetes Center,
  \url{http://www.pubhealth.ku.dk/~bxc}
} 
\seealso{
  \code{\link{apc.frame}}
}
\examples{
}
\keyword{hplot}