Creating abstract city maps for Leaflet usage

April 6, 2017
By

(This article was first published on R – Inside data, and kindly contributed to R-bloggers)

Leaflet is a great way to display spatial information in an interactive way. If you want to display the difference between different neighborhoods you would usually get the proper shapefiles on the web and connect your data to them. But sometimes it does not need detailed shapefiles and you want more abstraction to get your information across. I came up with the idea to draw my own little simplified polygons to get an abstract map of Hamburg.

AbtractHHtool

There are some great and free tools on the web to create your own polygons. I was using click2shp. You are just going to draw your polygons on a google map and afterwards you can export your polygons as a shapefile to use them from within R. Down below you find a little R script to display your polygons in a Shiny App.

#############################################################################################################################################
# PACKAGES
#############################################################################################################################################

require(leaflet)
require(shinythemes)
require(rgdal)
require(maptools)
require(rmapshaper)
require(shiny)
require(leaflet.extras)

#############################################################################################################################################
# UI
#############################################################################################################################################

shinyUI(
bootstrapPage(theme = shinytheme("united"),
 navbarPage(title="Where to live in Hamburg?",
 tabPanel("Karte",
 div(class="outer",

tags$style(type = "text/css", ".outer {position: fixed; top: 50px; left: 0; right: 0; bottom: 0; overflow: hidden; padding: 0}"),

leafletOutput("mymap", width = "100%", height = "100%")
)))))

#############################################################################################################################################
# SERVER
#############################################################################################################################################

shinyServer(
function(input, output, session) {

# setwd
setwd("YourPath")

# load your own shapes
hhshape <- readOGR(dsn = ".", layer = "click2shp_out_poly")

# load some data (could be anything)
data <- read.csv("anwohner.csv", sep = ";", header = T)
rownames(data) <- data$ID
hhshape <- SpatialPolygonsDataFrame(hhshape, data)

# remove rivers from sp file
hhshape <- hhshape[!(hhshape$Stadtteil %in% c("Alster","Elbe","Nix")), ]

# create a continuous palette function
pal <- colorNumeric(
 palette = "Blues",
 domain = [email protected]$Anwohner
)

# plot map
output$mymap <- renderLeaflet({ leaflet(options = leafletOptions(zoomControl = FALSE, minZoom = 11, maxZoom = 11, dragging = FALSE)) %>%
 setView(lng = 9.992924, lat = 53.55100, zoom = 11) %>%
 addPolygons(data = hhshape,
  fillColor = ~pal([email protected]$Anwohner), fillOpacity = 1, stroke = T, color = "white", opacity = 1, weight = 1.2, layerId = [email protected]$ID,
  highlightOptions = highlightOptions(color= "grey", opacity = 1, fillColor = "grey", stroke = T, weight = 12, bringToFront = T, sendToBack = TRUE),
  label=~stringr::str_c(Stadtteil,' ',"Anwohner:",formatC(Sicherheit, big.mark = ',', format='d')),
  labelOptions= labelOptions(direction = 'auto'))
})
})

This little R Code will give you the following result.

AbtractHH

Make sure you check out my Github for other data driven projects.

To leave a comment for the author, please follow the link and comment on their blog: R – Inside data.

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