Python一行代碼處理地理圍欄

最近在工作中遇到了這個一個需求，用戶設定地理圍欄，后台獲取到實時位置信息后通過與圍欄比較，判斷是否越界等。

這個過程需要用到數據協議為GEOjson，通過查閱資料后，發現python的shapely庫可以非常簡單的解決這個問題,接下來演示一下我處理這個問題的過程。

測試數據：

通過http://geojson.io/來獲得測試數據，如下圖，在地圖上繪制了一個多邊形設為地理圍欄，分別取了圍欄內外兩個點來進行測試。

得到GEOjson數據如下：

{
  "type": "FeatureCollection",
  "features": [
    {
      "type": "Feature",
      "properties": {},
      "geometry": {
        "type": "Polygon",
        "coordinates": [
          [
            [
              114.3458104133606,
              30.476167529462785
            ],
            [
              114.34512376785278,
              30.475575748963195
            ],
            [
              114.34576749801636,
              30.474540124433936
            ],
            [
              114.3467652797699,
              30.475363076967565
            ],
            [
              114.34693694114685,
              30.476102803645833
            ],
            [
              114.3458104133606,
              30.476167529462785
            ]
          ]
        ]
      }
    },
    {
      "type": "Feature",
      "properties": {},
      "geometry": {
        "type": "Point",
        "coordinates": [
          114.34605717658997,
          30.475584995561178
        ]
      }
    },
    {
      "type": "Feature",
      "properties": {},
      "geometry": {
        "type": "Point",
        "coordinates": [
          114.346604347229,
          30.476518897432545
        ]
      }
    }
  ]
}

安裝shapely

本測試基於python——python3.6

$ pip install shapely

windows安裝shapely會報錯

shapely解析地理圍欄

話不多說直接上代碼

from shapely.geometry import Point
from shapely.geometry.polygon import Polygon

point = Point(0.5, 0.5)
polygon = Polygon([(0, 0), (0, 1), (1, 1), (1, 0)])
print(polygon.contains(point))

下面是實際的實例：

from shapely.geometry import Point
from shapely.geometry.polygon import Polygon

polygon_data= [
            [
              114.3458104133606,
              30.476167529462785
            ],
            [
              114.34512376785278,
              30.475575748963195
            ],
            [
              114.34576749801636,
              30.474540124433936
            ],
            [
              114.3467652797699,
              30.475363076967565
            ],
            [
              114.34693694114685,
              30.476102803645833
            ],
            [
              114.3458104133606,
              30.476167529462785
            ]
          ]
          
point1 = Point([114.34605717658997,30.475584995561178])
point2 = Point([114.346604347229,30.476518897432545])
polygon = Polygon(polygon_data)
print(polygon.contains(point1))
print(polygon.contains(point2))

輸出結果：

True
False

這樣一來我們就快速的實現了，目標點是否在地理圍欄內的判斷。

總結

Python還是挺好用的：）

參考資料：

https://stackoverflow.com/questions/36399381/whats-the-fastest-way-of-checking-if-a-point-is-inside-a-polygon-in-python