写入几何

通过使用 插入和 更新游标，脚本可以在要素类中创建新要素或更新现有要素。脚本可以通过创建 点对象、填充要素属性和将要素放入 数组中来定义要素。然后，即可通过 面 (Polygon)、 折线 (Polyline)、 点几何 (PointGeometry) 或 多部件 (MultiPoint) 几何类使用该数组来设置要素几何。

import arcpy
fc = "c:/data/gdb.gdb/roads"
cursor = arcpy.da.InsertCursor(fc, ["SHAPE@"])
array = arcpy.Array([arcpy.Point(5997611.48964, 2069897.7022),
                     arcpy.Point(5997577.46097, 2069905.81145)])
polyline = arcpy.Polyline(array)

cursor.insertRow([polyline])

如上所示，单个几何部分可以由点数组定义。同样，可以使用同一游标从点数组的数组创建多部件要素，如下所示。

firstPart = arcpy.Array([arcpy.Point(5997624.6225, 2069868.8208),
                         arcpy.Point(5997674.94199, 2069833.81741)])
secondPart = arcpy.Array([arcpy.Point(5997616.44497, 2069862.32774),
                          arcpy.Point(5997670.57373, 2069824.67456)])

array = arcpy.Array([firstPart, secondPart])
multipartFeature = arcpy.Polyline(array)

cursor.insertRow([newGeometry2])

在写入点要素时，只有单个点对象用于设置点要素几何。使用 SHAPE@XY 令牌（以及 SHAPE@M 和 SHAPE@Z 令牌（如果需要的话）），也可更加轻松地创建点。

import arcpy

# fc is a point feature class
#
fc = "c:/data/gdb.gdb/stops"
cursor = arcpy.da.InsertCursor(fc, ["SHAPE@XY"])
xy = (5997594.4753, 2069901.75682)

cursor.insertRow([xy])

所有几何在写入要素类前都已经过验证。在插入几何前的几何简化过程中，将纠正各类问题（例如，不正确的环方向和自相交面以及其他问题）。

以下示例显示如何读取包含一系列线性坐标的坐标组（由 coordsList 定义），并使用它们创建新的要素类。

# Create a new line feature class using a text file of coordinates.
#   Each coordinate entry is semicolon delimited in the format of ID;X;Y
import arcpy
import os

# List of coordinates (ID, X, Y)
#
coordsList = [[1, -61845879.0968, 45047635.4861], 
              [1, -3976119.96791, 46073695.0451],
              [1, 1154177.8272, -25134838.3511],
              [1, -62051091.0086, -26160897.9101],
              [2, 17365918.8598, 44431999.7507],
              [2, 39939229.1582, 45252847.3979],
              [2, 41170500.6291, 27194199.1591],
              [2, 17981554.5952, 27809834.8945],
              [3, 15519011.6535, 11598093.8619],
              [3, 52046731.9547, 13034577.2446],
              [3, 52867579.6019, -16105514.2317],
              [3, 17160706.948, -16515938.0553]]

# The output feature class to be created
#
outFC = arcpy.GetParameterAsText(0)

# Get the template feature class
#
template = arcpy.GetParameterAsText(1)

cur = None
try:
    # Create the output feature class
    #
    arcpy.CreateFeatureclass_management(os.path.dirname(outFC),
                                        os.path.basename(outFC), 
                                        "POLYLINE", template)

    # Open an insert cursor for the new feature class
    #
    cur = arcpy.da.InsertCursor(outFC, ["SHAPE@"])

    # Create an array object needed to create features
    #
    array = arcpy.Array()

    # Initialize a variable for keeping track of a feature's ID.
    #
    ID = -1
    for coords in coordsList: 
        if ID == -1:
            ID = coords[0]

        # Add the point to the feature's array of points
        #   If the ID has changed, create a new feature
        #
        if ID != coords[0]:
            cur.insertRow([arcpy.Polyline(array)])
            array.removeAll()
        array.add(arcpy.Point(coords[1], coords[2], ID=coords[0]))
        ID = coords[0]

    # Add the last feature
    #
    cur.insertRow([arcpy.Polyline(array)])


except Exception as e:
   print e.message
finally:
    # Cleanup the cursor if necessary
    #
    if cur:
        del cur

通过创建由数组构成的数组并将其传递到 Polygon 类和 Polyline 类，可以创建多部分面要素和折线要素以及带有内部环的面要素。