# NOT RUN {
# 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)
crimesm <- reshape2::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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