map_data.Rd

% Generated by roxygen2 (4.0.0): do not edit by hand
\name{map_data}
\alias{map_data}
\title{Create a data frame of map data.}
\usage{
map_data(map, region = ".", exact = FALSE, ...)
}
\arguments{
\item{map}{name of map provided by the \pkg{maps} package.  These
include \code{\link[maps]{county}}, \code{\link[maps]{france}},
\code{\link[maps]{italy}}, \code{\link[maps]{nz}},
\code{\link[maps]{state}}, \code{\link[maps]{usa}},
\code{\link[maps]{world}}, \code{\link[maps]{world2}}.}

\item{region}{name of subregions to include.  Defaults to \code{.} which
includes all subregion.  See documentation for \code{\link[maps]{map}}
for more details.}

\item{exact}{should the \code{region} be treated as a regular expression
(\code{FALSE}) or as a fixed string (\code{TRUE}).}

\item{...}{all other arguments passed on to \code{\link[maps]{map}}}
}
\description{
Create a data frame of map data.
}
\examples{
if (require("maps")) {
states <- map_data("state")
arrests <- USArrests
names(arrests) <- tolower(names(arrests))
arrests$region <- tolower(rownames(USArrests))

choro <- merge(states, arrests, sort = FALSE, by = "region")
choro <- choro[order(choro$order), ]
qplot(long, lat, data = choro, group = group, fill = assault,
  geom = "polygon")
qplot(long, lat, data = choro, group = group, fill = assault / murder,
  geom = "polygon")
}
}