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、点几何 (PointGeometry) 或多点 (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([multipartFeature])
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 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)
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。