Hey there! Let's break down your two questions about Google Maps API and custom transit routes:

1. 如何通过Google Maps API添加自定义公交线路？ #

Depending on your needs, there are two practical approaches to add custom bus routes:

• 直接在地图上绘制可视化线路
  If you just need to display your custom bus route on a map, the easiest way is to use the Polyline class from the Maps JavaScript API. You'll need to collect the latitude/longitude coordinates of your route's key points (stops, turns), then create a Polyline instance with custom styling (like the classic blue bus route color) and attach it to your map. Here's a quick code snippet:

  // Assume you've already initialized your Google Map instance as `map`
  const customBusRoute = new google.maps.Polyline({
    path: [
      {lat: 40.712776, lng: -74.005974}, // Start point (e.g., Manhattan)
      {lat: 40.715200, lng: -74.008100}, // Mid-stop 1
      {lat: 40.718300, lng: -74.010200}  // End point
    ],
    strokeColor: "#0066CC",
    strokeOpacity: 0.9,
    strokeWeight: 6
  });
  customBusRoute.setMap(map);
  

• 利用Google My Maps创建并加载线路
  For more flexible route editing (like adding stop labels, sharing the route with others), you can build your custom bus route in Google My Maps first. Once you're done, export the map as a KML file, then use the KmlLayer from the Maps JavaScript API to load this KML onto your web map. This is great if you want a no-code way to design the route first before integrating it into your app.

2. 基于自定义公交线路计算两点间最短路径的可行性 #

Let's cut to the chase: Google Maps' native routing services (like the Directions API) don't support calculating paths based on user-defined custom transit networks—they rely exclusively on Google's own curated transit data. But don't worry, you still have options:

• Simple linear route scenario
  If your custom route is a single linear line (e.g., a shuttle route with no branching), you can use the Directions API with waypoints to force the path to follow your route. Just list key points along your custom bus route as waypoints, and the API will generate a path that goes through them. This works for basic use cases but isn't scalable for complex networks.

• Complex custom transit networks
  For multi-route systems with transfers between stops, you'll need to build your own path-finding logic:

  1. Model your network as a graph: Treat each bus stop as a node, and each segment between consecutive stops as an edge with a weight (e.g., travel time, distance).
  2. Implement a path-finding algorithm: Dijkstra's algorithm is a solid choice for finding shortest paths in networks with non-negative weights. If you want to optimize search speed, the A* algorithm is better—it uses a heuristic (like straight-line distance to the destination) to narrow down the search space.
  3. Leverage Google Maps APIs for helper data: Use the Geocoding API to convert addresses to coordinates, and the Distance Matrix API to calculate travel times/distances between stops (to set edge weights accurately).

内容的提问来源于stack exchange，提问作者Olteanu Radu