ArcMap

写入几何

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 Point 对象、填充要素属性和将要素放入 Array 中来定义要素。然后，即可通过 Polygon、Polyline、PointGeometry 或 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(-77.4349451, 37.5408265),
                     arcpy.Point(-78.6384349, 35.7780943)])
spatial_reference = arcpy.SpatialReference(4326)
polyline = arcpy.Polyline(array, spatial_reference)
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。

first_part = arcpy.Array([arcpy.Point(-77.4349451, 37.5408265),                          arcpy.Point(-78.6384349, 35.7780943)]) second_part = arcpy.Array([arcpy.Point(-79.7910143, 36.0786785),                           arcpy.Point(-80.8546435, 35.2315402)])
array = arcpy.Array([first_part, second_part]) spatial_reference = arcpy.SpatialReference(4326) multipart_feature = arcpy.Polyline(array, spatial_reference)
cursor.insertRow([multipart_feature])

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（而且高效）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 coords_list 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)
coords_list = [[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)
    # Access spatial reference of template to define spatial
    # reference of geometries
    spatial_reference = arcpy.Describe(template).spatialReference
    # 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 coords_list: 
        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
    polyline = arcpy.Polyline(array, spatial_reference)
    cur.insertRow([polyline])
except Exception as e:
    print(e)
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 Polyline 类和 Polygon 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。

根据坐标列表创建几何

也可以根据坐标列表创建几何。这种方法可以提高性能，因为其可免除创建几何对象的消耗。但是，仅限于单部件要素；对于面要素，则没有内部环。所有坐标应该以要素类的空间参考为单位。

在以下示例中，将根据 x,y 对列表创建单个面要素。

import arcpy
import os
coordinates = [(-117.2000424, 34.0555514), 
               (-117.2000788, 34.0592066), 
               (-117.1957315, 34.0592309), 
               (-117.1956951, 34.0556001)]
# Create a feature class with a spatial reference of GCS WGS 1984
result = arcpy.management.CreateFeatureclass(
    arcpy.env.scratchGDB, 
    "esri_square", "POLYGON", spatial_reference=4326)
feature_class = result[0]
# Write feature to new feature class
with arcpy.da.InsertCursor(feature_class, ['SHAPE@']) as cursor:
    cursor.insertRow([coordinates])

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