\name{scale_linetype}
\alias{scale_linetype}
\alias{scale_linetype_continuous}
\alias{scale_linetype_discrete}
\title{Scale for line patterns.}
\usage{
  scale_linetype(..., na.value = "blank")

  scale_linetype_continuous(...)

  scale_linetype_discrete(..., na.value = "blank")
}
\arguments{
  \item{na.value}{The linetype to use for \code{NA}
  values.}

  \item{...}{common discrete scale parameters: \code{name},
  \code{breaks}, \code{labels}, \code{na.value},
  \code{limits} and \code{guide}.  See
  \code{\link{discrete_scale}} for more details}
}
\description{
  Default line types based on a set supplied by Richard
  Pearson, University of Manchester.  Line types can not be
  mapped to continuous values.
}
\examples{
library(reshape2) # for melt
library(plyr) # for ddply
ecm <- melt(economics, id = "date")
rescale01 <- function(x) (x - min(x)) / diff(range(x))
ecm <- ddply(ecm, "variable", transform, value = rescale01(value))

qplot(date, value, data=ecm, geom="line", group=variable)
qplot(date, value, data=ecm, geom="line", linetype=variable)
qplot(date, value, data=ecm, geom="line", colour=variable)

# See scale_manual for more flexibility
}

