Trying out Leaflet

International Murders

Are among the data for analysis in the tidyTuesday for December 10, 2019. These are made for a map.

library(tidyverse)
library(leaflet)
library(stringr)
library(sf)
library(here)
library(widgetframe)
library(htmlwidgets)
library(htmltools)
options(digits = 3)
set.seed(1234)
theme_set(theme_minimal())
library(tidytuesdayR)
tuesdata <- tt_load(2019, week = 50)
murders <- tuesdata$gun_murders

There isn’t much data so it should make this a bit easier. Now for some data. As it happens, the best way I currently know how to do this is going to involve acquiring a spatial frame. There is one in the package tmap. First, to load it. My names are upper case.

library(tmap)
data("World")
World <- World %>% mutate(name = toupper(name))
murders[murders$country=="CZECH REPUBLIC","country"] <- "CZECH REP."
murders[murders$country=="HUNGRY","country"] <- "HUNGARY"
murders[murders$country=="REPUBLIC OF KOREA","country"] <- "KOREA"
World.M <- World %>% left_join(., murders, by = c( "name" = "country"))
World.M <- World.M %>% mutate(Murders = count)
tmap_style("white")
tmap_mode("view")
my.map <- tm_shape(World.M) +
    tm_polygons("Murders", title="", palette = "viridis") + tm_layout(panel.labels = "Gun Murders")
lf <- tmap_leaflet(my.map)
frameWidget(lf, height='600')

That’s convenient because I think I can also modify this for something else.

World.M.SF <- sf::as_Spatial(World.M)
l <- leaflet(World.M.SF) %>% setView(0,0,2) %>% addPolygons(weight = 1, smoothFactor = 0.5,
    opacity = 1.0, fillOpacity = 0.5,
    fillColor = ~colorQuantile("YlOrRd", Murders)(Murders),
    highlightOptions = highlightOptions(color = "white", weight = 2,
      bringToFront = TRUE))
esri <- grep("^Esri", providers, value = TRUE)
for (provider in esri) {
    l <- l %>% addProviderTiles(provider, group = provider)
}
l <- l %>%
    addLayersControl(baseGroups = names(esri),
                     options = layersControlOptions(collapsed = FALSE)) %>%
    addMiniMap(tiles = esri[[1]], toggleDisplay = TRUE,
               position = "bottomleft") %>%
    htmlwidgets::onRender("
    function(el, x) {
      var myMap = this;
      myMap.on('baselayerchange',
        function (e) {
          myMap.minimap.changeLayer(L.tileLayer.provider(e.name));
        })
    }")
# sf:::as_Spatial()
frameWidget(l, height = '600')
Avatar
Robert W. Walker
Associate Professor of Quantitative Methods

My research interests include causal inference, statistical computation and data visualisation.

Next
Previous

Related