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

我正在尝试将 Arcpy Polyline 对象作为值存储在 Python 字典中，以便可以在数据比较工具中快速引用它们。

问题：一旦我的脚本退出用于将折线对象保存到字典的 FOR 循环，Python 字典中的所有折线对象都具有相同的属性（它们应该都不同）。下面的每个函数都会在内存中创建五个不同的 Polyline 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：为什么折线对象属性 (.firstPoint .centroid .lastPoint) 在将它们分配为字典值后立即正确，但在 FOR 循环完成后不正确？具体来说，为什么 ReadData1 输出中最终 Polyline 对象的属性与 ReadData2 输出中的所有对象相关联？

代码：

import arcpy

def ReadData1(inShapefile):
    print arcpy.Describe(inShapefile).dataType, arcpy.Describe(inShapefile).shapeType
    sRows = arcpy.SearchCursor(inShapefile)
    dataDict = {}
    for row in sRows:
            dataDict[row.FID] = row.Shape
            print '%s || %s || %s' % (dataDict[row.FID].firstPoint, dataDict[row.FID].centroid, dataDict[row.FID].lastPoint)

def ReadData2(inShapefile):
    print arcpy.Describe(inShapefile).dataType, arcpy.Describe(inShapefile).shapeType
    sRows = arcpy.SearchCursor(inShapefile)
    dataDict = {}
    for row in sRows:
            dataDict[row.FID] = row.Shape
    for key in dataDict:
            print '%s || %s || %s' %(dataDict[key].firstPoint, dataDict[key].centroid, dataDict[key].lastPoint)

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：http: //dl.dropbox.com/u/67329940/TestShapefile.zip

ESRI 折线对象文档： http ://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#//000v000000n2000000

谢谢！

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2 回答 2

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您遇到了 ArcGIS 10.0 的一个已知问题。它已在 10.1 中修复，这就是我现在正在使用的。但是我曾经通过将形状转换为列表，然后像这样重新创建它来解决 10.0 上的问题：

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

您可以将 geojson 转换与 AsShape 一起使用并使用 AsShape 进行__geo_interface__重建，但这样会丢失空间参考。上述方法保留了空间参考。

于 2013-01-20T19:56:19.817 回答
1

您必须设置 arcpy.Geometry() 来存储您的 row.Shape ，否则您将丢失几何图形。这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
于 2013-06-21T14:37:54.063 回答