我一直在試圖調試這個問題,但無法做到這一點。我正在嘗試找到兩個對象Polygon
的交集。它大部分時間工作,但對於下列情況,它會產生以下例外情況:多邊形交點錯誤| Python Shapely
P1 area: 13.125721955
P2 area: 1.0
Traceback (most recent call last):
File "geom2d.py", line 235, in <module>
print p1.intersection(p2)
File "/usr/local/lib/python2.7/dist-packages/shapely/geometry/base.py", line 334, in intersection
return geom_factory(self.impl['intersection'](self, other))
File "/usr/local/lib/python2.7/dist-packages/shapely/topology.py", line 47, in __call__
"The operation '%s' produced a null geometry. Likely cause is invalidity of the geometry %s" % (self.fn.__name__, repr(this)))
shapely.geos.TopologicalError: The operation 'GEOSIntersection_r' produced a null geometry. Likely cause is invalidity of the geometry <shapely.geometry.polygon.Polygon object at 0x8e5ad6c>
代碼如下。
from shapely.geometry import Point,Polygon,MultiPolygon
poly1 = [(35.0041000000000011, -88.1954999999999956), (34.9917999999999978, -85.6068000000000069), (32.8404000000000025, -85.1756000000000029), (32.2593000000000032, -84.8927000000000049), (32.1535000000000011, -85.0341999999999985), (31.7946999999999989, -85.1358000000000033), (31.5199999999999996, -85.0438000000000045), (31.3384000000000000, -85.0836000000000041), (31.2092999999999989, -85.1069999999999993), (31.0023000000000017, -84.9943999999999988), (30.9953000000000003, -87.6008999999999958), (30.9422999999999995, -87.5926000000000045), (30.8538999999999994, -87.6256000000000057), (30.6744999999999983, -87.4072000000000031), (30.4404000000000003, -87.3687999999999931), (30.1463000000000001, -87.5240000000000009), (30.1545999999999985, -88.3863999999999947), (31.8938999999999986, -88.4742999999999995), (34.8937999999999988, -88.1020999999999930), (34.9478999999999971, -88.1721000000000004), (34.9106999999999985, -88.1461000000000041)]
poly2 = [(34.7998910000000024, -88.2202139999999986), (34.7998910000000024, -87.2202139999999986), (35.7998910000000024, -87.2202139999999986), (35.7998910000000024, -88.2202139999999986)]
p1 = Polygon(poly1)
p2 = Polygon(poly2)
print 'P1 area:',p1.area
print 'P2 area:',p2.area
print p1.intersection(p2)
由於它打印兩個多邊形的面積,我假設多邊形形成正確。我也(不知何故)打印第一個多邊形以確保它確實是一個簡單的多邊形。
任何人都可以請解釋爲什麼我得到這個異常?
編輯:我打印p1.is_valid,結果是False。有一些解釋here。搜索字符串is_valid
。它說
有效的多邊形可能不具有任何重疊的外部或內部環。
有人能解釋一下這是什麼意思,如果有可能的解決方法嗎? 順便說一句,我也注意到,如果我從poly1
刪除最後一個座標,整個事情就起作用了。也許整個座標列表使多邊形複雜。
有沒有辦法處理_complex_多邊形? – Nik
理想情況下,您可以將所有多邊形定義爲正確的開頭。既然這是對付美國的一個國家,而不是某種線索,我會認爲修正這將是更好的路線。但是,如果這是不可能的,你總是可以使用'p1.convex_hull'而不是'p1'。 'convex_hull'永遠是有效的,永不復雜。 –