data-raw/make_mapfile.R

In wmurphyrd/fiftystater: Map Data to Visualize the Fifty U.S. States with Alaska and Hawaii Insets

# This file is part of fiftystater.
#
# fiftytater is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, version 3.
#
# fiftystater is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with fiftystater  If not, see <http://www.gnu.org/licenses/>.

# Create map data with AK, HI inset.
# Inspired by http://stackoverflow.com/a/13767984
library(rgeos)
library(maptools)
library(rgdal)
library(ggplot2)
library(dplyr)

transform_state <- function(object, rot, scale, shift){
  object %>% elide(rotate = rot) %>%
    elide(scale = max(apply(bbox(object), 1, diff)) / scale) %>%
    elide(shift = shift)
}

#state shape file from
# http://www.arcgis.com/home/item.html?id=f7f805eb65eb4ab787a0a3e1116ca7e5
loc <- file.path(tempdir(), "stats_dat")
unzip("inst/extdata/states_21basic.zip", exdir = loc)
fifty_states_sp <- readOGR(dsn = loc, layer = "states", verbose = FALSE) %>%
  spTransform(CRS("+init=epsg:2163"))

alaska <- fifty_states_sp[fifty_states_sp$STATE_NAME == "Alaska", ] %>%
  transform_state(-35, 2.5, c(-2400000, -2100000))
proj4string(alaska) <- proj4string(fifty_states_sp)

hawaii <- fifty_states_sp[fifty_states_sp$STATE_NAME == "Hawaii", ] %>%
  transform_state(-35, .75, c(-1170000,-2363000))
proj4string(hawaii) <- proj4string(fifty_states_sp)

fifty_states <-
  fifty_states_sp[!fifty_states_sp$STATE_NAME %in% c("Alaska","Hawaii"), ] %>%
  rbind(alaska) %>%
  rbind(hawaii) %>%
  spTransform(CRS("+init=epsg:4326")) %>%
  fortify(region = "STATE_NAME") %>%
  mutate(id = tolower(id))

devtools::use_data(fifty_states, overwrite = TRUE)

get_box <- function(id) {
  fifty_states[fifty_states$id == id, c("long", "lat")] %>%
    as.matrix %>%
    bbox %>%
    t %>%
    # expand slightly to leave inner margin
    apply(2, `+`, c(-.5, .5)) %>%
    # rearrange corner coordinates into path coordinates
    `[`(c(1, 2, 2, 1, 1, 3, 3, 4, 4, 3)) %>%
    matrix(ncol = 2) %>%
    as.data.frame %>%
    setNames(c("x", "y")) %>%
    cbind(data.frame(id = id, stringsAsFactors = FALSE))
}

fifty_states_inset_boxes_data <- c("alaska", "hawaii") %>%
  lapply(get_box) %>%
  bind_rows

devtools::use_data(fifty_states_inset_boxes_data, overwrite = TRUE)