R/map_admissions.R

In epiforecasts/covid19.nhs.data: NHS Trust Level COVID-19 Data Aggregated to a Range of Spatial Scales

#' Map Admissions
#'
#' @description Map NHS Hospital aggregated admissions. By default this maps the
#' latest data provided.
#' @param admissions A data.frame of admissions data as produced by `get_dadmissions`. 
#' Must contain the following variables: `geo_code`, `date`, and `admissions`
#' @param date A date variable (or vector) indicating when to plot data for. If 
#' set to `NULL` then no date filter is applied 
#' @param scale_fill A `ggplot2` `scale_fill` used to define the fill colours 
#' used in the map. The default is: 
#' `scale_fill_viridis_c(option = "viridis", direction = -1, na.value = "grey80")`.
#' @inheritParams summarise_mapping
#' @importFrom ggplot2 ggplot geom_sf aes scale_fill_viridis_c labs theme_void theme guides guide_colorbar
#' @importFrom dplyr filter inner_join
#' @importFrom lubridate as_date
#' @import sf 
#' @return A map of Covid-19 admissions in England 
#' @export
map_admissions <- function(admissions, shapefile, date, scale_fill) {
  
  if (missing(date)) {
    max_date <- max(admissions$date)
  }else if (!is.null(date)) {
    max_date <- as_date(date)
  }else {
    max_date <- NULL
  }
  
  if (missing(scale_fill)) {
    scale_fill <- scale_fill_viridis_c(option = "viridis", direction = -1, 
                                       na.value = "grey80")
  }
  
  if (!is.null(max_date)) {
    admissions <- admissions %>% 
      filter(date %in% max_date)
  }
  
  g <- shapefile %>%
    inner_join(admissions, by = "geo_code") %>% 
    ggplot() +
    geom_sf(data = shapefile, lwd = 0.3, col = "grey60") +
    geom_sf(aes(fill = admissions), lwd = 0.3, col = "grey20") +
    scale_fill +
    theme_void() +
    guides(fill = guide_colorbar(title = "Admissions")) +
    theme(legend.position = "bottom", legend.justification = "left")
  
  return(g)
}