How To: Add a Leaflet Map To a Zeppelin Notebook

[#1]

This article will give a quick demonstration to add Leaflet maps to an Angular paragraph in Zeppelin.

Background: Leaflet Maps

Leaflet is an open-source JavaScript library for interactive maps. Leaflet is designed with simplicity, performance and usability in mind.

Step 1: Adding a map to a Zeppelin notebook.

Code Source:

%angular 
<link rel="stylesheet" href="https://unpkg.com/leaflet@1.0.3/dist/leaflet.css" />
<div id="map" style="height: 800px; width: 100%"> </div>
<script type="text/javascript">
function initMap() {
    var map = L.map('map').setView([33.415, -111.831], 6);
    L.tileLayer('http://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png', {
        attribution: 'Map data © <a href="http://openstreetmap.org">OpenStreetMap</a> contributors',
        maxZoom: 15,
        minZoom: 3
    }).addTo(map);
    var geoMarkers = L.layerGroup().addTo(map);
   
}
if (window.L) {
    initMap();
} else {
    console.log('Loading Leaflet library');
    var sc = document.createElement('script');
    sc.type = 'text/javascript';
    sc.src='https://unpkg.com/leaflet@1.0.3/dist/leaflet.js';
    sc.onload = initMap;
    sc.onerror = function(err) { alert(err); }
    document.getElementsByTagName('head')[0].appendChild(sc);
}
</script>

Step 2: Adding markers to the map manually.

Code Source:

%angular 
<link rel="stylesheet" href="https://unpkg.com/leaflet@1.0.3/dist/leaflet.css" />
<div id="map" style="height: 800px; width: 100%"> </div>
<script type="text/javascript">
function initMap() {
    var map = L.map('map').setView([33.415, -111.831], 12);
    L.tileLayer('http://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png', {
        attribution: 'Map data © <a href="http://openstreetmap.org">OpenStreetMap</a> contributors',
        maxZoom: 15,
        minZoom: 3
    }).addTo(map);
    var geoMarkers = L.layerGroup().addTo(map);
    var lat = 31.603513;
    var long = -94.655487;
    var lat1 = 38.381572;
    var long1 = -121.49440;
    var LJIcon = L.icon({
    iconUrl: 'https://upload.wikimedia.org/wikipedia/en/f/ff/SFA_Athletics_logo.png',
    iconSize: [38, 38],
    });
    var goldIcon = L.icon({
    iconUrl: 'http://www.pngmart.com/files/3/Lakshmi-Gold-Coin-PNG-Transparent-Image.png',
    iconSize: [20, 20],
    });
   var marker = L.marker([ lat, long ],{icon: LJIcon} ).bindPopup("Nacogdoches, Tx" +" : " + "21ABC").addTo(map);
    var marker1 = L.marker([ lat1, long1 ],{icon: goldIcon} ).bindPopup("Sacramento, Ca" +" : " + "34DGC").addTo(geoMarkers)
}
if (window.L) {
    initMap();
} else {
    console.log('Loading Leaflet library');
    var sc = document.createElement('script');
    sc.type = 'text/javascript';
    sc.src='https://unpkg.com/leaflet@1.0.3/dist/leaflet.js';
    sc.onload = initMap;
    sc.onerror = function(err) { alert(err); }
    document.getElementsByTagName('head')[0].appendChild(sc);
}
</script>

Step 3: Adding map markers from a GeoJSON file.

Code Source:

%angular 
<link rel="stylesheet" href="https://unpkg.com/leaflet@1.0.3/dist/leaflet.css" />
<div id="map" style="height: 800px; width: 100%"> </div>
<script type="text/javascript">
function initMap() {
    var map = L.map('map').setView([33.415, -111.831], 8);
    L.tileLayer('http://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png', {
        attribution: 'Map data © <a href="http://openstreetmap.org">OpenStreetMap</a> contributors',
        maxZoom: 15,
        minZoom: 3
    }).addTo(map);
    var geoMarkers = L.layerGroup().addTo(map);
    
      $.getJSON("https://raw.githubusercontent.com/BrooksIan/DS_GTDB/master/json/Mesa.geojson",function(data){
          L.geoJson(data).addTo(map);
      });
}
if (window.L) {
    initMap();
} else {
    console.log('Loading Leaflet library');
    var sc = document.createElement('script');
    sc.type = 'text/javascript';
    sc.src='https://unpkg.com/leaflet@1.0.3/dist/leaflet.js';
    sc.onload = initMap;
    sc.onerror = function(err) { alert(err); }
    document.getElementsByTagName('head')[0].appendChild(sc);
}
</script>

[#2]

have you connected to data from SQL?

[#3]

I haven't tried that yet. I have got markers from an existing file working at this point in time.

[#4]

This is soooo cool!

[#5]

I've found that in Zeppelin 0.7.0 the geoJSON needs to be obtained without credentials, otherwise an access control error results : "The value of the 'Access-Control-Allow-Origin' header in the response must not be the wildcard '*' when the request's credentials mode is 'include'" which is I guess new behaviour in Zeppelin.

As there doesn't seem to be a way to configure $.getJSON to do this, load it as follows :

$.ajax({ 
  url: "https://raw.githubusercontent.com/BrooksIan/DS_GTDB/master/json/Mesa.geojson",
  dataType: "json",
  xhrFields: { withCredentials: false }
})
.done( function( data ) {
  L.geoJson( data ).addTo( map );
});

Hope this helps, Simon

[#6]

I've also found that a Zeppelin style hides any geoJSON boundary type overlays. The offending rule seems to be the following, removing this in chrome dev tools makes the overlay appear. YMMV...

..\zeppelin-web\src\app\notebook\paragraph\paragraph.css

.paragraph div svg {
    width: 100%;
}