Geometry (arcpy)

Zusammenfassung

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

Diskussion

Bei vielen Workflows der Geoverarbeitung möchten Sie eventuell bestimmte Vorgänge mit Koordinaten- und Geometriedaten ausführen, jedoch nicht unbedingt eine neue (temporäre) Feature-Class erstellen, diese mit Cursorn füllen, die Feature-Class verwenden und dann die vorläufige Feature-Class wieder löschen. Sie können anstelle von Eingabe und Ausgabe auch Geometrieobjekte verwenden und so die Geoverarbeitung vereinfachen. Geometrieobjekte können von Grund auf neu mit Geometry-, Multipoint-, PointGeometry-, Polygon- oder Polyline-Classes erstellt werden.

Syntax

Geometry (geometry, inputs, {spatial_reference}, {has_z}, {has_m})

Parameter	Erläuterung	Datentyp
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
spatial_reference	The spatial reference of the new geometry. (Der Standardwert ist None)	SpatialReference
has_z	The Z state: True for geometry if Z is enabled and False if it is not. (Der Standardwert ist False)	Boolean
has_m	The M state: True for geometry if M is enabled and False if it is not. (Der Standardwert ist False)	Boolean

Eigenschaften

Eigenschaft	Erläuterung	Datentyp
JSON (Schreibgeschützt)	Returns a JSON representation of the geometry as a string. Tipp: The returned string can be converted to a dictionary by Python's eval function.	String
WKB (Schreibgeschützt)	Returns the well-known binary (WKB) representation for OGC geometry. It provides a portable representation of a geometry value as a contiguous stream of bytes.	Bytearray
WKT (Schreibgeschützt)	Returns the well-known text (WKT) representation for OGC geometry. It provides a portable representation of a geometry value as a text string.	String
area (Schreibgeschützt)	The area of a polygon feature. Empty for all other feature types.	Double
centroid (Schreibgeschützt)	The true centroid if it is within or on the feature; otherwise, the label point is returned. Returns a point object.	Point
extent (Schreibgeschützt)	The extent of the geometry.	Extent
firstPoint (Schreibgeschützt)	The first coordinate point of the geometry.	Point
hullRectangle (Schreibgeschützt)	A space-delimited string of the coordinate pairs of the convex hull rectangle.	String
isMultipart (Schreibgeschützt)	True, if the number of parts for this geometry is more than one.	Boolean
labelPoint (Schreibgeschützt)	The point at which the label is located. The labelPoint is always located within or on a feature.	Point
lastPoint (Schreibgeschützt)	The last coordinate of the feature.	Point
length (Schreibgeschützt)	The length of the linear feature. Zero for point and multipoint feature types.	Double
length3D (Lesen und schreiben)	The 3D length of the linear feature. Zero for point and multipoint feature types.	Double
partCount (Schreibgeschützt)	The number of geometry parts for the feature.	Integer
pointCount (Schreibgeschützt)	The total number of points for the feature.	Integer
trueCentroid (Schreibgeschützt)	The center of gravity for a feature.	Point
type (Schreibgeschützt)	The geometry type: polygon, polyline, point, multipoint, multipatch, dimension, or annotation.	String

Methodenübersicht

Methode	Erläuterung
boundary ()	Constructs the boundary of the geometry.
buffer (distance)	Constructs a polygon at a specified distance from the geometry.
clip (envelope)	Constructs the intersection of the geometry and the specified extent.
contains (second_geometry)	Gibt an, ob die Basisgeometrie die Vergleichsgeometrie enthält. contains ist das Gegenteil von within. Only True relationships are shown in this illustration.
convexHull ()	Constructs the geometry that is the minimal bounding polygon such that all outer angles are convex.
crosses (second_geometry)	Gibt an, ob die beiden Geometrien sich in einer Geometrie mit einem geringeren Shape-Typ überschneiden. Zwei Polylinien kreuzen sich, wenn sie nur Punkte gemeinsam haben, von denen mindestens einer kein Endpunkt ist. Eine Polylinie und ein Polygon kreuzen sich, wenn sie im Inneren des Polygons eine Polylinie oder einen Punkt (für eine vertikale Linie) gemeinsam haben, die bzw. der nicht der gesamten Polylinie entspricht. Only True relationships are shown in this illustration.
difference (other)	Constructs the geometry that is composed only of the region unique to the base geometry but not part of the other geometry. The following illustration shows the results when the red polygon is the source geometry.
disjoint (second_geometry)	Gibt an, ob die Basis- und die Vergleichsgeometrie keine gemeinsamen Punkte aufweisen. Zwei Geometrien überschneiden sich, wenn disjoint den Wert False zurückgibt. Only True relationships are shown in this illustration.
distanceTo (other)	Returns the minimum distance between two geometries. If the geometries intersect, the minimum distance is 0. Both geometries must have the same projection.
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. This is a 2D comparison only; M and Z values are ignored. Only True relationships are shown in this illustration.
getArea (type)	Returns the area of the feature using a measurement type.
getLength (measurement_type)	Returns the length of the feature using a measurement type.
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.
intersect (other, dimension)	Constructs a geometry that is the geometric intersection of the two input geometries. Different dimension values can be used to create different shape types. The intersection of two geometries of the same shape type is a geometry containing only the regions of overlap between the original geometries. For faster results, test if the two geometries are disjoint before calling intersect.
overlaps (second_geometry)	Gibt an, üb die Überschneidung der beiden Geometrien denselben Shape-Typ wie eine der Eingabegeometrien aufweist, aber keiner der Eingabegeometrien entspricht. Only True relationships are shown in this illustration.
positionAlongLine (value, {use_percentage})	Returns a point on a line at a specified distance from the beginning of the line.
projectAs (spatial_reference, {transformation_name})	Projects a geometry and optionally applies a geotransformation. To project, the geometry needs to have a spatial reference, and not have an UnknownCoordinateSystem. The new spatial reference system passed to the method defines the output coordinate system. If either spatial reference is unknown the coordinates will not be changed. The Z- and measure values are not changed by the ProjectAs method.
symmetricDifference (other)	Constructs the geometry that is the union of two geometries minus the instersection of those geometries. The two input geometries must be the same shape type.
touches (second_geometry)	Gibt an, ob sich die Grenzen der Geometrien überschneiden. Zwei Geometrien berühren sich, wenn die Schnittmenge der Geometrien nicht leer, die Schnittmengen der Innenbereiche jedoch leer ist. Ein Punkt berührt beispielsweise eine Polylinie nur, wenn der Punkt lagegleich mit einem der Endpunkte der Polylinie ist. Only True relationships are shown in this illustration.
union (other)	Constructs the geometry that is the set-theoretic union of the input geometries. The two geometries being unioned must be the same shape type.
within (second_geometry)	Gibt an, ob sich die Basisgeometrie innerhalb der Vergleichsgeometrie befindet. Der within-Operator stellt das Gegenteil von contains dar. Only True relationships are shown in this illustration.

Methoden

boundary ()

Rückgabewert

Datentyp	Erläuterung
Object	A polygon's boundary is a polyline. A polyline's boundary is a multipoint, corresponding to the endpoints of the line. A point or multipoint's boundary is an empty point or multipoint.

buffer (distance)

Parameter	Erläuterung	Datentyp
distance	The buffer distance. The buffer distance is in the same units as the geometry that is being buffered. A negative distance can only be specified against a polygon geometry.	Double

Rückgabewert

Datentyp	Erläuterung
Polygon	The buffered polygon geometry.

clip (envelope)

Parameter	Erläuterung	Datentyp
envelope	An extent object used to define the clip extent.	Extent

Rückgabewert

Datentyp	Erläuterung
Object	An output geometry clipped to the specified extent.

contains (second_geometry)

Parameter	Erläuterung	Datentyp
second_geometry	A second geometry.	Object

Rückgabewert

Datentyp	Erläuterung
Boolean	Der boolesche Rückgabetyp True gibt an, dass diese Geometrie die zweite Geometrie enthält.

convexHull ()

Rückgabewert

Datentyp	Erläuterung
Object	The resulting geometry. The convex hull of a single point is the point itself.

crosses (second_geometry)

Parameter	Erläuterung	Datentyp
second_geometry	A second geometry.	Object

Rückgabewert

Datentyp	Erläuterung
Boolean	Der boolesche Rückgabetyp "True" gibt an, dass sich die beiden Geometrien in einer Geometrie mit einem geringeren Shape-Typ schneiden.

difference (other)

Parameter	Erläuterung	Datentyp
other	A second geometry.	Object

Rückgabewert

Datentyp	Erläuterung
Object	The resulting geometry.

disjoint (second_geometry)

Parameter	Erläuterung	Datentyp
second_geometry	A second geometry.	Object

Rückgabewert

Datentyp	Erläuterung
Boolean	Der boolesche Rückgabetyp "True" gibt an, dass die beiden Geometrien keine gemeinsamen Punkte aufweisen.

distanceTo (other)

Parameter	Erläuterung	Datentyp
other	A second geometry.	Object

Rückgabewert

Datentyp	Erläuterung
Double	The distance between the two geometries.

equals (second_geometry)

Parameter	Erläuterung	Datentyp
second_geometry	A second geometry.	Object

Rückgabewert

Datentyp	Erläuterung
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.

getArea (type)

Parameter	Erläuterung	Datentyp
type	PLANAR measurements reflect the projection of geographic data onto the 2D surface (in other words, they will not take into account the curvature of the earth). GEODESIC, GREAT_ELLIPTIC, LOXODROME, and PRESERVE_SHAPE measurement types may be chosen as an alternative, if desired. GEODESIC —The shortest line between any two points on the earth's surface on a spheroid (ellipsoid). One use for a geodesic line is when you want to determine the shortest distance between two cities for an airplane's flight path. This is also known as a great circle line if based on a sphere rather than an ellipsoid. GREAT_ELLIPTIC —The line on a spheroid (ellipsoid) defined by the intersection at the surface by a plane that passes through the center of the spheroid and the start and endpoints of a segment. This is also known as a great circle when a sphere is used. LOXODROME —A loxodrome is not the shortest distance between two points but instead defines the line of constant bearing, or azimuth. Great circle routes are often broken into a series of loxodromes, which simplifies navigation. This is also known as a rhumb line. PLANAR —Planar measurement use 2D Cartesian mathematics to calculate lengths and areas. This option is only available when measuring in a projected coordinate system and the 2D plane of that coordinate system will be used as the basis for the measurements. PRESERVE_SHAPE —This type calculates the area or length of the geometry on the surface of the Earth ellipsoid, for geometry defined in a projected or geographic coordinate system. This option preserves the shape of the geometry in its coordinate system.	String

Rückgabewert

Datentyp	Erläuterung
Double	The area of the feature. Areas are always returned in square meters.

getLength (measurement_type)

Parameter	Erläuterung	Datentyp
measurement_type	PLANAR measurements reflect the projection of geographic data onto the 2D surface (in other words, they will not take into account the curvature of the earth). GEODESIC, GREAT_ELLIPTIC, LOXODROME, and PRESERVE_SHAPE measurement types may be chosen as an alternative, if desired. GEODESIC —The shortest line between any two points on the earth's surface on a spheroid (ellipsoid). One use for a geodesic line is when you want to determine the shortest distance between two cities for an airplane's flight path. This is also known as a great circle line if based on a sphere rather than an ellipsoid. GREAT_ELLIPTIC —The line on a spheroid (ellipsoid) defined by the intersection at the surface by a plane that passes through the center of the spheroid and the start and endpoints of a segment. This is also known as a great circle when a sphere is used. LOXODROME —A loxodrome is not the shortest distance between two points but instead defines the line of constant bearing, or azimuth. Great circle routes are often broken into a series of loxodromes, which simplifies navigation. This is also known as a rhumb line. PLANAR —Planar measurement use 2D Cartesian mathematics to calculate lengths and areas. This option is only available when measuring in a projected coordinate system and the 2D plane of that coordinate system will be used as the basis for the measurements. PRESERVE_SHAPE —This type calculates the area or length of the geometry on the surface of the Earth ellipsoid, for geometry defined in a projected or geographic coordinate system. This option preserves the shape of the geometry in its coordinate system.	String

Rückgabewert

Datentyp	Erläuterung
Double	The length of the linear feature. Lengths are always returned in meters.

getPart ({index})

Parameter	Erläuterung	Datentyp
index	The index position of the geometry.	Integer

Rückgabewert

Datentyp	Erläuterung
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.

intersect (other, dimension)

Parameter	Erläuterung	Datentyp
other	The second geometry.	Object
dimension	The topological dimension (shape type) of the resulting geometry. 1 —A zero-dimensional geometry (point or multipoint). 2 —A one-dimensional geometry (polyline). 4 —A two-dimensional geometry (polygon).	Integer

Rückgabewert

Datentyp	Erläuterung
Object	A new geometry (point, multipoint, polyline, or polygon) that is the geometric intersection of the two input geometries.

overlaps (second_geometry)

Parameter	Erläuterung	Datentyp
second_geometry	A second geometry.	Object

Rückgabewert

Datentyp	Erläuterung
Boolean	Der boolesche Rückgabetyp True gibt an, dass die Überschneidung der beiden Geometrien dieselbe Dimension wie eine der Eingabegeometrien aufweist.

positionAlongLine (value, {use_percentage})

Parameter	Erläuterung	Datentyp
value	The distance along the line. If the distance is less than zero, then the starting point of the line will be returned; if the distance is greater than the length of the line, then the end point of the line will be returned.	Double
use_percentage	The distance may be specified as a fixed unit of measure or a ratio of the length of the line. If True, value is used as a percentage; if False, value is used as a distance. (Der Standardwert ist False)	Boolean

Rückgabewert

Datentyp	Erläuterung
PointGeometry	The point on the line at a specified distance from the beginning of the line.

projectAs (spatial_reference, {transformation_name})

Parameter	Erläuterung	Datentyp
spatial_reference	The new spatial reference. This can be a SpatialReference object or the coordinate system name.	SpatialReference
transformation_name	The geotransformation name.	String

Rückgabewert

Datentyp	Erläuterung
Object	The projected geometry.

symmetricDifference (other)

Parameter	Erläuterung	Datentyp
other	A second geometry.	Object

Rückgabewert

Datentyp	Erläuterung
Object	The resulting geometry.

touches (second_geometry)

Parameter	Erläuterung	Datentyp
second_geometry	A second geometry.	Object

Rückgabewert

Datentyp	Erläuterung
Boolean	Der boolesche Rückgabetyp True gibt an, dass sich die Grenzen der Geometrien überschneiden.

union (other)

Parameter	Erläuterung	Datentyp
other	A second geometry.	Object

Rückgabewert

Datentyp	Erläuterung
Object	The resulting geometry.

within (second_geometry)

Parameter	Erläuterung	Datentyp
second_geometry	A second geometry.	Object

Rückgabewert

Datentyp	Erläuterung
Boolean	Der boolesche Rückgabetyp True gibt an, dass diese Geometrie in der zweiten Geometrie enthalten ist.

Codebeispiel

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