How to create a countries map with your own data

This tutorial demonstrates the process of merging your own personalized data with the MapTiler Countries dataset, allowing you to create a choropleth map. The MapTiler Countries dataset primarily consists of information regarding the administrative divisions of countries and their territories around the world.

For this specific example, we will be creating a choropleth map that showcases the population of some European countries.

NPM module setup

  1. Install the npm package.

    
 npm install --save @maptiler/sdk

  2. Include the CSS file.

    If you have a bundler that can handle CSS, you can import the CSS

    
 import "@maptiler/sdk/dist/maptiler-sdk.css";

    or include it with a <link /> in the head of the document via the CDN

    
 <link href='https://cdn.maptiler.com/maptiler-sdk-js/v4.1.0/maptiler-sdk.css' rel='stylesheet' />

  3. Include the following code in your JavaScript file (Example: app.js).

    
 import * as maptilersdk from '@maptiler/sdk';

 maptilersdk.config.apiKey = 'YOUR_MAPTILER_API_KEY_HERE';
 const map = new maptilersdk.Map({
   container: 'map', // container's id or the HTML element to render the map
   style: maptilersdk.MapStyle.DATAVIZ.LIGHT,
      
   center: [13.39, 52.51], // starting position [lng, lat]
   zoom: 2, // starting zoom
      
 });

  4. Replace YOUR_MAPTILER_API_KEY_HERE with your own API key. Make sure to secure the key before you publish it.

  5. The next is up to you. You can center your map wherever you desire (modifying the starting position) and set an appropriate zoom level (modifying the starting zoom) to match your users’ needs. Additionally, you can change the map’s look (by updating the source URL); choose from a range of visually appealing map styles from our extensive MapTiler standard maps, or create your own to truly differentiate your application.

  6. Add event handler for map load event. You will add code to create a vector source and a vector layer in this handler.

    
 map.on('load', function() {

 });

  7. Create vector source. The following snippet creates vector source for the MapTiler Countries dataset.

    
 map.on('load', function() {
   map.addSource('statesData', {
     type: 'vector',
     url: `https://api.maptiler.com/tiles/countries/tiles.json`
   });
 });

  8. Get the id of the first symbol layer. We want to include the vector layer below the map labels. That means we need to know the id of the first symbol layer so we can include the vector layer before this layer.

    
 // Find the id of the first symbol layer in the map style
 const layers = map.getStyle().layers;
 const firstSymbolId = layers.find(layer => layer.type === 'symbol').id;

  9. Add the vector layer. We need to include firsSymbolId to the map.addLayer function to display the vector under the maps labels

    
 map.addLayer(
   {
     'id': 'countries',
     'source': 'statesData',
     'source-layer': 'administrative',
     'type': 'fill',
     'paint': {
         'fill-color': '#6B7C93',
         'fill-opacity': 1,
         'fill-outline-color': '#000'
     }
   },
   firstSymbolId   
 );

  10. Filter the data to only show the countries. Add a filter to the layer to only display level 0 items.

    
 map.addLayer(
   {
     'id': 'countries',
     'source': 'statesData',
     'source-layer': 'administrative',
     'type': 'fill',
     'filter': ['==', 'level', 0],
     'paint': {
         'fill-color': '#6B7C93',
         'fill-opacity': 1,
         'fill-outline-color': '#000'
     }
   },
   firstSymbolId   
 );

  11. Prepare your data. Each feature in the dataset has its own identification for pairing. You need to mark your data with the same identifiers as is stored by features. We will use the iso_n3 identifier for countries. Alternatively, you can use one of the properties: name, country codes (ISO A2), or wiki data-id. Check out the Countries dataset schema to see the available fields.

    
 const vizData = {
   "8":{"name":"Albania","population":2829741},
   "40":{"name":"Austria","population":8932664},
   "56":{"name":"Belgium","population":11566041},
   "100":{"name":"Bulgaria","population":6916548},
   "191":{"name":"Croatia","population":4036355},
   "196":{"name":"Cyprus","population":896005},
   "203":{"name":"Czechia","population":10701777},
   "208":{"name":"Denmark","population":5840045},
   "233":{"name":"Estonia","population":1330068},
   "246":{"name":"Finland","population":5533793},
   "250":{"name":"France","population":67439599},
   "276":{"name":"Germany","population":83155031},
   "300":{"name":"Greece","population":10682547},
   "348":{"name":"Hungary","population":9730772},
   "352":{"name":"Iceland","population":368792},
   "372":{"name":"Ireland","population":5006907},
   "380":{"name":"Italy","population":59257566},
   "428":{"name":"Latvia","population":1893223},
   "438":{"name":"Liechtenstein","population":39055},
   "440":{"name":"Lithuania","population":2795680},
   "442":{"name":"Luxembourg","population":634730},
   "470":{"name":"Malta","population":516100},
   "499":{"name":"Montenegro","population":620739},
   "528":{"name":"Netherlands","population":17475415},
   "578":{"name":"Norway","population":5391369},
   "616":{"name":"Poland","population":37840001},
   "620":{"name":"Portugal","population":10298252},
   "642":{"name":"Romania","population":19186201},
   "688":{"name":"Serbia","population":6871547},
   "703":{"name":"Slovakia","population":5459781},
   "705":{"name":"Slovenia","population":2108977},
   "724":{"name":"Spain","population":47394223},
   "752":{"name":"Sweden","population":10379295},
   "756":{"name":"Switzerland","population":8667088},
   "792":{"name":"Turkey","population":83614362},
   "807":{"name":"North Macedonia","population":2068808}
 };

  12. Join the data to coresponding features. Use querySourceFeatures to get all features from the layer for visualization. We are also filtering for all countries with ['==', 'level', 0] using style expressions. The second part of the following code goes throw these features and adds attributes from our data array (vizData) to relevant features.

    
 function setStates() {
   const countries = map.querySourceFeatures('statesData', {
     sourceLayer: 'administrative',
     filter: ['all', ['==', 'level', 0]],
   });
   countries.forEach(country => {
     if(country.id && vizData[country.id]) {
       map.setFeatureState({
         source: 'statesData',
         sourceLayer: 'administrative',
         id: country.id
       }, {
         population: vizData[country.id].population
       });
     }
   });
   if (countries.length !== 0) {
     map.off('data', afterLoad);
   }
 }

  13. Create a function that validates that the country dataset is loaded to call the setStates function.

    
 function afterLoad() {
   if (map.getSource('statesData') && map.isSourceLoaded('statesData')) {
     setStates();
   }
 }

  14. Add event handler for map data event. Call the afterLoad function

    
 map.on('data', afterLoad);

  15. Create a choropleth map based on the population attribute. Change the fill-color property of the layer.

    
 map.addLayer(
   {
     'id': 'countries',
     'source': 'statesData',
     'source-layer': 'administrative',
     'type': 'fill',
     'filter': ['==', 'level', 0],
     'paint': {
         'fill-color': ['case',
           ['!=', ['to-number', ['feature-state', 'population']], 0],
           ['interpolate', ['linear'], ['feature-state', 'population'], 
             5000000, 'rgba(222,235,247,1)', 90000000, 'rgba(49,130,189,1)'
           ],
           'rgba(0, 0, 0, 0)'
         ],
         'fill-opacity': 1,
         'fill-outline-color': '#000'
     }
   },
   firstSymbolId   
 );

  16. Display a popup when clicking on the vector layer and show the information of the age attribute.

    
 map.on('click', 'countries', function (e) {
   new maptilersdk.Popup()
     .setLngLat(e.lngLat)
     .setHTML(`<h3>Population</h3><p>${e.features[0].state.population.toLocaleString()}</p>`)
     .addTo(map);
 });

  17. To make our map more user friendly, we will change the cursor when hovering over a geometry in the vector layer to indicate to the user that they can click on it.

    
 // Change the cursor to a pointer when the mouse is over the layer.
 map.on('mouseenter', 'countries', function () {
     map.getCanvas().style.cursor = 'pointer';
 });

 // Change it back to a pointer when it leaves.
 map.on('mouseleave', 'countries', function () {
     map.getCanvas().style.cursor = '';
 });

Learn more

Check out the tutorials How to use and filter data for MapTiler Countries and How to display an interactive choropleth map legend control.

Visit the MapTiler Countries schema to know how it is organized into different thematic layers and which attribute and values each layer contains.

Read the following How-tos related to choropleth maps:

How to style a choropleth map in Edit Tool

Prepare GeoJSON with attributes for choropleth map and upload GeoJSON to MapTiler

How to use and filter data for MapTiler Countries

Countries filter

Tutorials

Filter MapTiler Countries data to create choropleth maps.

Point filtering by property

Point filtering by property

Examples

Filter features in real time by property.

Interactive choropleth map

Interactive choropleth map

Examples

Use events and feature states to create a interactive choropleth map.

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