public initMap(mapElement: ElementRef, search: ElementRef, options: MapOptions) {
return this.init().pipe(
  switchMap(() =>
    this.createGoogleMap(mapElement.nativeElement, search.nativeElement, options)
  ),
  exhaustMap(() =>
    forkJoin(
      this.subscribeToDrawingEvents('circlecomplete').pipe(
        map(d => console.log(d))
        ),
      this.subscribeToCenterChangeEvents('center_changed').pipe(
          map(d => console.log(d))
          ),
      this.subscribeToRadiusChangeEvents('radius_changed').pipe(
            map(d => console.log(d))
            ),
      this.subscribeToSearchboxEvents('places_changed')
    )
  )
);

ngOnInit() {
this.option = {
  center: this.center ? this.center : { lat: 0, lng: 0 },
  zoom: this.zoom ? this.zoom : 4,
  markers: this.markers ? this.markers : []
};
this.subscribe_event$ = this.service.initMap(this.googleMap, this.searchInput, this.option);
this.subscribe_event$.subscribe();

this.subscribeToCenterChangeEvents('center_changed').pipe(
          map(d => console.log(d))
          ),