python arcgis Geometry

Geometry

ArcGIS 10

汇总

Geometry objects define a spatial location and an associated geometric shape.

讨论

在许多地理处理工作流中，您可能需要使用坐标和几何信息运行特定操作，但不一定想经历创建新（临时）要素类、使用光标填充要素类、使用要素类，然后删除临时要素类的过程。可以使用几何对象替代输入和输出，从而使地理处理变得更简单。可以使用 Geometry、Multipoint、PointGeometry、Polygon 或 Polyline 类从头开始创建几何对象。

语法

Geometry (geometry, inputs, {spatialReference}, {hasZ}, {hasM})

参数	说明	数据类型
geometry	The geometry type: point, polygon, polyline, or multipoint.	String
inputs	The coordinates used to create the object. The datatype can be either Point or Array objects.	Object
spatialReference	The spatial reference of the new geometry. (默认值为None)	SpatialReference
hasZ	The Z state: True for geometry if Z is enabled and False if it is not. (默认值为False)	Boolean
hasM	The M state: True for geometry if M is enabled and False if it is not. (默认值为False)	Boolean

属性

属性	说明	数据类型
area (只读)	The area of a polygon feature. Empty for all other feature types.	Double
centroid (只读)	The true centroid if it is within or on the feature; otherwise, the label point is returned. Returns a point object.	Point
extent (只读)	The extent of the geometry.	Extent
firstPoint (只读)	The first coordinate point of the geometry.	Point
hullRectangle (只读)	A space-delimited string of the coordinate pairs of the convex hull rectangle.	String
isMultipart (只读)	True, if the number of parts for this geometry is more than one.	Boolean
labelPoint (只读)	The point at which the label is located. The labelPoint is always located within or on a feature.	Point
lastPoint (只读)	The last coordinate of the feature.	Point
length (只读)	The length of the linear feature. Zero for point, multipoint feature types.	Double
partCount (只读)	The number of geometry parts for the feature.	Integer
pointCount (只读)	The total number of points for the feature.	Integer
trueCentroid (只读)	The center of gravity for a feature.	Point
type (只读)	The geometry type: polygon, polyline, point, multipoint, multipatch, dimension, annotation.	String

方法概述

方法	说明
contains (second_geometry)	Indicates if the base geometry contains the comparison geometry. contains is the opposite of within. Only True relationships are shown in this illustration.
crosses (second_geometry)	Indicates if the two geometries intersect in a geometry of a lesser shape type. Two polylines cross if they share only points in common, at least one of which is not an endpoint. A polyline and an polygon cross if they share a polyline or a point (for vertical line) in common on the interior of the polygon which is not equivalent to the entire polyline. Only True relationships are shown in this illustration.
disjoint (second_geometry)	Indicates if the base and comparison geometries share no points in common. Two geometries intersect if disjoint returns False. Only True relationships are shown in this illustration.
equals (second_geometry)	Indicates if the base and comparison geometries are of the same shape type and define the same set of points in the plane. Only True relationships are shown in this illustration.
getPart ({index})	Returns an array of point objects for a particular part of geometry or an array containing a number of arrays, one for each part.
overlaps (second_geometry)	Indicates if the intersection of the two geometries has the same shape type as one of the input geometries and is not equivalent to either of the input geometries. Only True relationships are shown in this illustration.
touches (second_geometry)	Indicates if the boundaries of the geometries intersect. Two geometries touch when the intersection of the geometries is not empty, but the intersection of their interiors is empty. For example, a point touches a polyline only if the point is coincident with one of the polyline end points. Only True relationships are shown in this illustration.
within (second_geometry)	Indicates if the base geometry is within the comparison geometry. within is the opposite operator of contains. Only True relationships are shown in this illustration.

方法

contains (second_geometry)

参数	说明	数据类型
second_geometry	A second geometry.	Object

返回值

数据类型	说明
Boolean	A return Boolean value of True indicates this geometry contains the second geometry.

crosses (second_geometry)

参数	说明	数据类型
second_geometry	A second geometry.	Object

返回值

数据类型	说明
Boolean	A return Boolean value of True indicates the two geometries intersect in a geometry of a lesser shape type.

disjoint (second_geometry)

参数	说明	数据类型
second_geometry	A second geometry.	Object

返回值

数据类型	说明
Boolean	A return Boolean value of True indicates that the two geometries share no points in common.

equals (second_geometry)

参数	说明	数据类型
second_geometry	A second geometry.	Object

返回值

数据类型	说明
Boolean	A return Boolean value of True indicates that the two geometries are of the same shape type and define the same set of points in the plane.

getPart ({index})

参数	说明	数据类型
index	The index position of the geometry.	Integer

返回值

数据类型	说明
Array	getPart returns an array of point objects for a particular part of the geometry if an index is specified. If an index is not specified, an array containing an array of point objects for each geometry part is returned.

overlaps (second_geometry)

参数	说明	数据类型
second_geometry	A second geometry.	Object

返回值

数据类型	说明
Boolean	A return Boolean value of True indicates the intersection of the two geometries has the same dimension as one of the input geometries.

touches (second_geometry)

参数	说明	数据类型
second_geometry	A second geometry.	Object

返回值

数据类型	说明
Boolean	A return Boolean value of True indicates the boundaries of the geometries intersect.

within (second_geometry)

参数	说明	数据类型
second_geometry	A second geometry.	Object

返回值

数据类型	说明
Boolean	A return Boolean value of True indicates this geometry is contained within the second geometry.

代码示例

Geometry example

When you set the output parameter of a geoprocessing tool to a empty Geometry object, the tool will return a list of Geometry objects.

import arcpy

# Create an empty Geometry object
#
g = arcpy.Geometry()

# Run the CopyFeatures tool, setting the output to the geometry object.  GeometryList
#  is returned as a list of geometry objects.
#  
geometryList = arcpy.CopyFeatures_management("c:/data/streets.shp", g)

# Walk through each geometry, totalling the length
#
length = 0
for geometry in geometryList:
    length += geometry.length

print "Total length: %f" % length