points - values - heatmap

        
      this.http.get('assets/letting.json').subscribe(data => {
        this.lettings = data['data'];
        const heatmapData = [];
        this.lettings.map(x => {
          heatmapData.push({
            location: new maps.LatLng(x[24], x[23]),
            weight: parseInt(x[15], 10)
          });
        });
        const heatmap = new maps.visualization.HeatmapLayer({
          data: heatmapData
        });
        heatmap.set('gradient', customGradient);
        heatmap.set('radius', 70);
        heatmap.set('opacity', 1);
        heatmap.setMap(this.map);
      });