- add code for quering sos api

src/app/services/marker.service.ts

@@ -0,0 +1,53 @@
+import { Injectable } from '@angular/core';
+
+import { HttpClient } from '@angular/common/http';
+import * as L from 'leaflet';
+
+// @Injectable({
+//     // declares that this service should be created
+//   // by the root application injector.
+//   providedIn: 'root'
+// })
+@Injectable()
+export class MarkerService {
+
+  private capitalsUrl: string = 'https://raw.githubusercontent.com/do-community/angular-leaflet-example/master/src/assets/data/usa-capitals.geojson';
+ 
+  constructor(private http: HttpClient) {
+    // this.http = http;
+  }
+
+  static scaledRadius(val: number, maxVal: number): number {
+    return 20 * (val / maxVal);
+  }
+
+//   makeCapitalMarkers(map: L.map): void {
+//     this.http.get(this.capitalsUrl).subscribe((res: any) => {
+//       for (const c of res.features) {
+//         const lon = c.geometry.coordinates[0];
+//         const lat = c.geometry.coordinates[1];
+//         const marker = new L.marker([lat, lon]);
+
+//         marker.addTo(map);
+//       }
+//     });
+//   }
+
+  makeCapitalCircleMarkers(map: L.Map): void {
+    this.http.get(this.capitalsUrl).subscribe((res: any) => {
+
+      let maxPop = Math.max(...res.features.map(x => x.properties.population), 0);
+
+      for (const c of res.features) {
+        const lon = c.geometry.coordinates[0];
+        const lat = c.geometry.coordinates[1];
+        // const circle = L.circleMarker([lat, lon]);
+        let circle = L.circleMarker([lat, lon], {
+          radius: MarkerService.scaledRadius(c.properties.population, maxPop)
+        });
+        circle.addTo(map);
+      }
+    });
+  }
+
+}