Geometry (arcpy)

Summary

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

Discussion

In many geoprocessing workflows, you may need to run a specific operation using coordinate and geometry information but don't necessarily want to go through the process of creating a new (temporary) feature class, populating the feature class with cursors, using the feature class, then deleting the temporary feature class. Geometry objects can be used instead for both input and output to make geoprocessing simpler. Geometry objects can be created from scratch using Geometry, Multipoint, PointGeometry, Polygon, or Polyline classes.

Syntax

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

Parameter	Explanation	Data Type
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. (The default value is None)	SpatialReference
has_z	The Z state: True for geometry if Z is enabled and False if it is not. (The default value is False)	Boolean
has_m	The M state: True for geometry if M is enabled and False if it is not. (The default value is False)	Boolean

Properties

Property	Explanation	Data Type
JSON (Read Only)	Returns a JSON representation of the geometry as a string. Tip: The returned string can be converted to a dictionary using Python's json.loads function.	String
WKB (Read Only)	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 (Read Only)	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 (Read Only)	The area of a polygon feature. Empty for all other feature types.	Double
centroid (Read Only)	The true centroid if it is within or on the feature; otherwise, the label point is returned. Returns a point object.	Point
extent (Read Only)	The extent of the geometry.	Extent
firstPoint (Read Only)	The first coordinate point of the geometry.	Point
hullRectangle (Read Only)	A space-delimited string of the coordinate pairs of the convex hull rectangle.	String
isMultipart (Read Only)	True, if the number of parts for this geometry is more than one.	Boolean
labelPoint (Read Only)	The point at which the label is located. The labelPoint is always located within or on a feature.	Point
lastPoint (Read Only)	The last coordinate of the feature.	Point
length (Read Only)	The length of the linear feature. Zero for point and multipoint feature types.	Double
length3D (Read and Write)	The 3D length of the linear feature. Zero for point and multipoint feature types.	Double
partCount (Read Only)	The number of geometry parts for the feature.	Integer
pointCount (Read Only)	The total number of points for the feature.	Integer
spatialReference (Read Only)	The spatial reference of the geometry.	SpatialReference
trueCentroid (Read Only)	The center of gravity for a feature.	Point
type (Read Only)	The geometry type: polygon, polyline, point, multipoint, multipatch, dimension, or annotation.	String

Method Overview

Method	Explanation
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)	Indicates if the base geometry contains the comparison geometry. contains is the opposite of 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)	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.
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)	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.
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)	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.
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)	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.
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)	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.

Methods

boundary ()

Return Value

Data Type	Explanation
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	Explanation	Data Type
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

Return Value

Data Type	Explanation
Polygon	The buffered polygon geometry.

clip (envelope)

Parameter	Explanation	Data Type
envelope	An extent object used to define the clip extent.	Extent

Return Value

Data Type	Explanation
Object	An output geometry clipped to the specified extent.

contains (second_geometry)

Parameter	Explanation	Data Type
second_geometry	A second geometry.	Object

Return Value

Data Type	Explanation
Boolean	A return Boolean value of True indicates this geometry contains the second geometry.

convexHull ()

Return Value

Data Type	Explanation
Object	The resulting geometry. The convex hull of a single point is the point itself.

crosses (second_geometry)

Parameter	Explanation	Data Type
second_geometry	A second geometry.	Object

Return Value

Data Type	Explanation
Boolean	A return Boolean value of True indicates the two geometries intersect in a geometry of a lesser shape type.

difference (other)

Parameter	Explanation	Data Type
other	A second geometry.	Object

Return Value

Data Type	Explanation
Object	The resulting geometry.

disjoint (second_geometry)

Parameter	Explanation	Data Type
second_geometry	A second geometry.	Object

Return Value

Data Type	Explanation
Boolean	A return Boolean value of True indicates that the two geometries share no points in common.

distanceTo (other)

Parameter	Explanation	Data Type
other	A second geometry.	Object

Return Value

Data Type	Explanation
Double	The distance between the two geometries.

equals (second_geometry)

Parameter	Explanation	Data Type
second_geometry	A second geometry.	Object

Return Value

Data Type	Explanation
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	Explanation	Data Type
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

Return Value

Data Type	Explanation
Double	The area of the feature. Areas are always returned in square meters.

getLength (measurement_type)

Parameter	Explanation	Data Type
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

Return Value

Data Type	Explanation
Double	The length of the linear feature. Lengths are always returned in meters.

getPart ({index})

Parameter	Explanation	Data Type
index	The index position of the geometry.	Integer

Return Value

Data Type	Explanation
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	Explanation	Data Type
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

Return Value

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

overlaps (second_geometry)

Parameter	Explanation	Data Type
second_geometry	A second geometry.	Object

Return Value

Data Type	Explanation
Boolean	A return Boolean value of True indicates the intersection of the two geometries has the same dimension as one of the input geometries.

positionAlongLine (value, {use_percentage})

Parameter	Explanation	Data Type
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. (The default value is False)	Boolean

Return Value

Data Type	Explanation
PointGeometry	The point on the line at a specified distance from the beginning of the line.

projectAs (spatial_reference, {transformation_name})

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

Return Value

Data Type	Explanation
Object	The projected geometry.

symmetricDifference (other)

Parameter	Explanation	Data Type
other	A second geometry.	Object

Return Value

Data Type	Explanation
Object	The resulting geometry.

touches (second_geometry)

Parameter	Explanation	Data Type
second_geometry	A second geometry.	Object

Return Value

Data Type	Explanation
Boolean	A return Boolean value of True indicates the boundaries of the geometries intersect.

union (other)

Parameter	Explanation	Data Type
other	A second geometry.	Object

Return Value

Data Type	Explanation
Object	The resulting geometry.

within (second_geometry)

Parameter	Explanation	Data Type
second_geometry	A second geometry.	Object

Return Value

Data Type	Explanation
Boolean	A return Boolean value of True indicates this geometry is contained within the second geometry.

Code Sample

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

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

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

print("Total length: {0}".format(length))