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% Generated by roxygen2 (4.0.1): do not edit by hand
\name{geom_map}
\alias{geom_map}
\title{Polygons from a reference map.}
\usage{
geom_map(mapping = NULL, data = NULL, map, stat = "identity", ...)
}
\arguments{
\item{map}{Data frame that contains the map coordinates. This will
typically be created using \code{\link{fortify}} on a spatial object.
It must contain columns \code{x} or \code{long}, \code{y} or
\code{lat}, and \code{region} or \code{id}.}
\item{mapping}{The aesthetic mapping, usually constructed with
\code{\link{aes}} or \code{\link{aes_string}}. Only needs to be set
at the layer level if you are overriding the plot defaults.}
\item{data}{A layer specific dataset - only needed if you want to override
the plot defaults.}
\item{stat}{The statistical transformation to use on the data for this
layer.}
\item{...}{other arguments passed on to \code{\link{layer}}. This can
include aesthetics whose values you want to set, not map. See
\code{\link{layer}} for more details.}
}
\description{
Does not affect position scales.
}
\section{Aesthetics}{
\Sexpr[results=rd,stage=build]{ggplot2:::rd_aesthetics("geom", "map")}
}
\examples{
# When using geom_polygon, you will typically need two data frames:
# one contains the coordinates of each polygon (positions), and the
# other the values associated with each polygon (values). An id
# variable links the two together
ids <- factor(c("1.1", "2.1", "1.2", "2.2", "1.3", "2.3"))
values <- data.frame(
id = ids,
value = c(3, 3.1, 3.1, 3.2, 3.15, 3.5)
)
positions <- data.frame(
id = rep(ids, each = 4),
x = c(2, 1, 1.1, 2.2, 1, 0, 0.3, 1.1, 2.2, 1.1, 1.2, 2.5, 1.1, 0.3,
0.5, 1.2, 2.5, 1.2, 1.3, 2.7, 1.2, 0.5, 0.6, 1.3),
y = c(-0.5, 0, 1, 0.5, 0, 0.5, 1.5, 1, 0.5, 1, 2.1, 1.7, 1, 1.5,
2.2, 2.1, 1.7, 2.1, 3.2, 2.8, 2.1, 2.2, 3.3, 3.2)
)
ggplot(values) + geom_map(aes(map_id = id), map = positions) +
expand_limits(positions)
ggplot(values, aes(fill = value)) +
geom_map(aes(map_id = id), map = positions) +
expand_limits(positions)
ggplot(values, aes(fill = value)) +
geom_map(aes(map_id = id), map = positions) +
expand_limits(positions) + ylim(0, 3)
# Better example
crimes <- data.frame(state = tolower(rownames(USArrests)), USArrests)
library(reshape2) # for melt
crimesm <- melt(crimes, id = 1)
if (require(maps)) {
states_map <- map_data("state")
ggplot(crimes, aes(map_id = state)) +
geom_map(aes(fill = Murder), map = states_map) +
expand_limits(x = states_map$long, y = states_map$lat)
last_plot() + coord_map()
ggplot(crimesm, aes(map_id = state)) +
geom_map(aes(fill = value), map = states_map) +
expand_limits(x = states_map$long, y = states_map$lat) +
facet_wrap( ~ variable)
}
}
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