In JohnCoene/echarts4r: Create Interactive Graphs with 'Echarts JavaScript' Version 5

knitr::opts_chunk$set(
  collapse = TRUE,
  comment = "#>"
)

library(echarts4r)

e_common(
    font_family = "Raleway"
)

Introduction

You will find 215 maps in the companion package echarts4r.maps. However, since you may need different kinds of maps i.e.: at the citiy or county level that are not included in this package, you may need to get the detailed map data from third-party source such as gadm.org. This document shows how to make your own GeoJSON file which can be used in e_map_register.

Packages

These are packages to help you building such maps

• sp: spatial data management package.
• raster: get spatial data from gadm.org.
• geojsonio: convert spatial data into json format.
• rmapshaper: simplify the spatial data.

library(echarts4r)
library(sp)
library(raster)
library(geojsonio)
library(rmapshaper)

Example

Get India map data from gadm website, this command need network available, it will download the rds data to the current directory.

india_sp <- raster::getData('GADM', country = 'INDIA', level = 2) 
india_sp |> 
  head() |> 
  knitr::kable()

Note that you can then combine maps with raster::union(map1, map2) or with the em_maps function from the echarts4r.maps package. Then convert the SpatialPolygonsDataFrame into GeoJSON with geojsonio: this will take a long time as the map is very detailed.

india_json <- geojsonio::geojson_list(india_sp)
print(object.size(india_json), units = "Mb")

Therefore we can simplify the map to make it smaller.

india_small <- rmapshaper::ms_simplify(india_sp, keep = 0.05) 
india_json_small <- geojsonio::geojson_list(india_small)
print(object.size(india_json_small), units = "Mb") 

The function raster::getData gives each polygon a NAME_* property (where * is the level specified) rather than just name. The tooltip will not display properly unless we use the nameMap to point to that property, by default echarts expects the name property.

Now we can use the GeoJSON with e_map_register.

# plot 
e_charts() |>
  e_map_register("India", india_json_small) |>
  e_map(map = "India", nameProperty = "NAME_2")

JohnCoene/echarts4r documentation built on Feb. 23, 2024, 9:21 a.m.