Python 将arcpy多段线对象用作字典值时丢失的形状信息

环境：Win 7 Enterprise，SP1 | ArcGIS Desktop 10.0（Python 2.6.5）

我试图将Arcpy多段线对象作为值存储在Python字典中，以便在数据比较工具中快速引用它们

问题: 脚本退出用于将多段线对象保存到字典的FOR循环后，Python字典中的所有多段线对象都具有相同的属性（它们都应该是不同的）。下面的每个函数在内存中创建五个不同的多段线对象，但是，ReadData1对象的属性都不同，而ReadData2对象的属性都相同

问题: 为什么多段线对象属性（.firstPoint.centroid.lastPoint）在作为字典值指定后立即正确，但在FOR循环完成后不正确？具体来说，为什么ReadData1输出中的最终多段线对象的属性与ReadData2输出中的所有对象关联

代码：

输出：

>>> ReadData1(r'U:\...\TestShapefile.shp')
ShapeFile Polyline
7590284.40892474 668332.064064309 NaN NaN || 7590324.42908373 666711.247624955 NaN NaN || 7592576.19984799 665145.042311657 NaN NaN
7592021.15673377 667418.928618325 NaN NaN || 7592961.14910463 667427.880926619 NaN NaN || 7593901.1414755 667436.833234913 NaN NaN
7594098.09225797 668421.587147249 NaN NaN || 7595183.14682072 667013.998170435 NaN NaN || 7596891.21244568 665682.180809295 NaN NaN
7593793.71377597 665897.03620835 NaN NaN || 7593516.19221886 665261.422319479 NaN NaN || 7593238.67066174 664625.808430607 NaN NaN
7590302.31354132 663336.676036276 NaN NaN || 7593453.20916493 663528.873380711 NaN NaN || 7596533.12011392 663873.814533914 NaN NaN

>>> ReadData2(r'U:\...\TestShapefile.shp')
ShapeFile Polyline
7590302.31354132 663336.676036276 NaN NaN || 7593453.20916493 663528.873380711 NaN NaN || 7596533.12011392 663873.814533914 NaN NaN
7590302.31354132 663336.676036276 NaN NaN || 7593453.20916493 663528.873380711 NaN NaN || 7596533.12011392 663873.814533914 NaN NaN
7590302.31354132 663336.676036276 NaN NaN || 7593453.20916493 663528.873380711 NaN NaN || 7596533.12011392 663873.814533914 NaN NaN
7590302.31354132 663336.676036276 NaN NaN || 7593453.20916493 663528.873380711 NaN NaN || 7596533.12011392 663873.814533914 NaN NaN
7590302.31354132 663336.676036276 NaN NaN || 7593453.20916493 663528.873380711 NaN NaN || 7596533.12011392 663873.814533914 NaN NaN

测试形状文件：

ESRI多段线对象文档：

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谢谢

您在ArcGIS 10.0中遇到了一个已知问题。它在10.1中被修复，这就是我现在使用的。但我过去常常在10.0上通过将形状转换为列表，然后像这样重新创建来解决这个问题：

tractfc = 'c:/temp/test.shp'

rows = arcpy.SearchCursor(tractfc)
dct = {}
for row in rows:
    shp = row.Shape
    lst = list(shp)
    ary = arcpy.Array(lst)
    newshp = arcpy.Polyline(ary, shp.spatialReference)
    dct[row.FID] = newshp

for k in dct:
    print k, dct[k].firstPoint

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您可以将geojson转换与

\uuuuu geo\u interface\uuuu

一起使用，并使用AsShape进行重建，但这样会丢失空间引用。上述方法保留了空间参照

必须设置一个arcpy.Geometry（）来存储行.Shape，否则将丢失几何体。下面是上面代码中的一个示例

tractfc = 'c:/temp/test.shp' 
rows = arcpy.SearchCursor(tractfc)
dct = {}

for row in rows:
   g = arcpy.Geometry()
   g = row.Shape
   dct[row.FID] = g

for k in dct:
   print k, dct[k].firstPoint.X, dct[k].firstPoint.Y

我发现了这一点：但它并没有提供一个明确的解决方案——也许是时候升级Arcpy了。

tractfc = 'c:/temp/test.shp' 
rows = arcpy.SearchCursor(tractfc)
dct = {}

for row in rows:
   g = arcpy.Geometry()
   g = row.Shape
   dct[row.FID] = g

for k in dct:
   print k, dct[k].firstPoint.X, dct[k].firstPoint.Y