在Angular Google Map中应该有多个时只显示一个标记

这是HTML部分：

<agm-map [latitude]="lat" [longitude]="long" [zoom] = 16>
<agm-marker *ngFor="let m of latlongs; let i = index"
[latitude]="m.lat"
[longitude]="m.long"
[markerDraggable]="m.draggable"></agm-marker>

</agm-map>

打字稿代码在这里：

this.service.getData().subscribe(data => {
  let json: any[] = []; 
  json["data"] = data.json().map(it => {
    it["category"] = "location";
    it["gallery"] = ["../assets/img/area.png"];
    return it;
  });

  for(let i = 0; i < json["data"].length; i++){
    this.mapInfos.push({lat: +json["data"][i].lat,long: +json["data"][i].long});
  }

  this.latlongs = this.mapInfos;

});

我正在为我的项目使用角度4