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#' Create a county-level choropleth
#' @export
#' @importFrom dplyr left_join
#' @include usa.R
CountyChoropleth = R6Class("CountyChoropleth",
inherit = USAChoropleth,
public = list(
# this map looks better with an outline of the states added
add_state_outline = TRUE,
# initialize with us state map
initialize = function(user.df)
{
if (!requireNamespace("choroplethrMaps", quietly = TRUE)) {
stop("Package choroplethrMaps is needed for this function to work. Please install it.", call. = FALSE)
}
data(county.map, package="choroplethrMaps", envir=environment())
data(county.regions, package="choroplethrMaps", envir=environment())
# USAChoropleth requires a column called "state" that has full lower case state name (e.g. "new york")
county.map$state = merge(county.map, county.regions, sort=FALSE, by.x="region", by.y="region")$state.name
super$initialize(county.map, user.df)
# by default, show all states on the map
data(state.map, package="choroplethrMaps", envir=environment())
private$zoom = unique(state.map$region)
if (private$has_invalid_regions)
{
warning("Please see ?county.regions for a list of mappable regions")
}
},
# user.df has county FIPS codes for regions, but subsetting happens at the state level
clip = function()
{
# remove regions not on the map before doing the merge
data(county.regions, package="choroplethrMaps", envir=environment())
self$user.df = self$user.df[self$user.df$region %in% county.regions$region, ]
self$user.df$state = merge(self$user.df, county.regions, sort=FALSE, all.X=TRUE, by.x="region", by.y="region")$state.name
self$user.df = self$user.df[self$user.df$state %in% private$zoom, ]
self$user.df$state = NULL
self$map.df = self$map.df[self$map.df$state %in% private$zoom, ]
}
)
)
#' Create a choropleth of US Counties
#'
#' The map used is county.map in the choroplethrMaps package. See country.regions
#' in the choroplethrMaps package for an object which can help you coerce your regions
#' into the required format.
#'
#' @param df A data.frame with a column named "region" and a column named "value". Elements in
#' the "region" column must exactly match how regions are named in the "region" column in county.map.
#' @param title An optional title for the map.
#' @param legend An optional name for the legend.
#' @param num_colors The number of colors to use on the map. A value of 0 uses
#' a divergent scale (useful for visualizing negative and positive numbers), A
#' value of 1 uses a continuous scale (useful for visualizing outliers), and a
#' value in [2, 9] will use that many quantiles.
#' @param state_zoom An optional vector of states to zoom in on. Elements of this vector must exactly
#' match the names of states as they appear in the "region" column of ?state.regions.
#' @param county_zoom An optional vector of counties to zoom in on. Elements of this vector must exactly
#' match the names of counties as they appear in the "region" column of ?county.regions.
#' @param reference_map If true, render the choropleth over a reference map from Google Maps.
#'
#' @examples
#' \dontrun{
#' # default parameters
#' data(df_pop_county)
#' county_choropleth(df_pop_county,
#' title = "US 2012 County Population Estimates",
#' legend = "Population")
#'
#' # zoom in on california and add a reference map
#' county_choropleth(df_pop_county,
#' title = "California County Population Estimates",
#' legend = "Population",
#' state_zoom = "california",
#' reference_map = TRUE)
#'
#' # continuous scale
#' data(df_pop_county)
#' county_choropleth(df_pop_county,
#' title = "US 2012 County Population Estimates",
#' legend = "Population",
#' num_colors = 1,
#' state_zoom = c("california", "oregon", "washington"))
#'
#' library(dplyr)
#' library(choroplethrMaps)
#' data(county.regions)
#'
#' # show the population of the 5 counties (boroughs) that make up New York City
#' nyc_county_names = c("kings", "bronx", "new york", "queens", "richmond")
#' nyc_county_fips = county.regions %>%
#' filter(state.name == "new york" & county.name %in% nyc_county_names) %>%
#' select(region)
#' county_choropleth(df_pop_county,
#' title = "Population of Counties in New York City",
#' legend = "Population",
#' num_colors = 1,
#' county_zoom = nyc_county_fips$region)
#' }
#' @export
#' @importFrom Hmisc cut2
#' @importFrom stringr str_extract_all
#' @importFrom ggplot2 ggplot aes geom_polygon scale_fill_brewer ggtitle theme theme_grey element_blank geom_text
#' @importFrom ggplot2 scale_fill_continuous scale_colour_brewer
#' @importFrom grid unit
county_choropleth = function(df, title="", legend="", num_colors=7, state_zoom=NULL, county_zoom=NULL, reference_map=FALSE)
{
# user can only zoom in by one of the zoom options
if (!is.null(state_zoom) && !is.null(county_zoom))
{
stop("You cannnot set state_zoom and county_zoom at the same time.")
}
if (!is.null(county_zoom))
{
c = CountyZoomChoropleth$new(df)
c$title = title
c$legend = legend
c$set_num_colors(num_colors)
c$set_zoom(county_zoom)
if (reference_map) {
c$render_with_reference_map()
} else {
c$render()
}
} else {
c = CountyChoropleth$new(df)
c$title = title
c$legend = legend
c$set_num_colors(num_colors)
c$set_zoom(state_zoom)
if (reference_map) {
if (is.null(state_zoom))
{
stop("Reference maps do not currently work with maps that have insets, such as maps of the 50 US States.")
}
c$render_with_reference_map()
} else {
c$render()
}
}
}
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