通过网格拆分高德地图

  因为爬虫需要,如大众点评通过距离获取商铺,以及高德poi获取有数量限制。就想到通过网格的方式,把高德地图拆分成一个一个的格子,获取对应的经纬度,然后通过对应的经纬度去爬取收据。

思路:  

  首先获取城市的边界范围,根据边界画出一个矩形。然后通过 new AMap.LngLat获取相应的点。但是考虑到绘制的会远大于该城市实际范围,在城市内部再绘制一个矩形。外围矩形每五公里拆分一次,内部矩形每公里拆分一次。

主要代码如下

var x1 = new AMap.LngLat(left_lng, left_lat)
var x2 = new AMap.LngLat(right_lng, left_lat)
var y = new AMap.LngLat(left_lng, right_lat)
var center_x1 = new AMap.LngLat(center_left_lng, center_left_lat)
var center_x2 = new AMap.LngLat(center_right_lng, center_left_lat)
var center_y = new AMap.LngLat(center_left_lng, center_right_lat)
var x_distance = x1.distance(x2);
var y_distance = x1.distance(y);
var center_x_distance = center_x1.distance(center_x2);
var center_y_distance = center_x1.distance(center_y);
console.log(x_distance, y_distance)
console.log(center_x_distance, center_y_distance)
drawGrad(x_distance, y_distance);

function drawGrad(x, y) {//x,y代表的是距离
var x_total = Math.floor(x / km);//首尾,故点多1
var y_total = Math.floor(y / km);
console.log(x_total, y_total)
for (var i = 0; i < x_total + 1; i++) {
  for (var j = 0; j < y_total + 1; j++) {
    let point = southWest.offset(km * i, -km * j)
    //在内部矩形,则跳过
    if ((center_left_lng <= point.lng && point.lng <= center_right_lng) && (center_right_lat <= point.lat && point.lat <= center_left_lat)) {
      continue
    }
    pointsObj[i + "_" + j] = point.lng + ',' + point.lat
    if (i > 0 && j > 0) {
      let last_point = pointsObj[(i - 1) + '_' + (j - 1)];
      if(!last_point){
        continue
      }
      arrList.push(last_point+ '|' + pointsObj[i + '_' + j])
    }
    var bounds2 = new AMap.Bounds(southWest, point)
    var rectangle2 = new AMap.Rectangle({
      bounds: bounds2,
      strokeColor: '#000',
      strokeWeight: 1,
      strokeStyle: 'dashed',
      fillColor: 'transparent',
    })
    rectangle2.setMap(map)

    if (i == x_total && j == y_total) {
      // console.error(Date.parse(new Date()))
      console.log(arrList.length)
      console.log(JSON.stringify(arrList))
    }
  }
}
}

完整代码已上传GitHub,并上传了辅助找边界的页面。https://github.com/c870275682/gaode_tool

posted @ 2019-01-28 15:09  无敌小坑笔  阅读(2641)  评论(0编辑  收藏