Polygon

Summary

A Polygon object is a closed shape defined by a connected sequence of x,y coordinate pairs.

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

Polygon (inputs, {spatialReference}, {hasZ}, {hasM})

Parameter	Explanation	Data Type
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. (The default value is None)	SpatialReference
hasZ	The Z state: True for geometry if Z is enabled and False if it is not. (The default value is False)	Boolean
hasM	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
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, 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
trueCentroid (Read Only)	The center of gravity for a feature.	Point
type (Read Only)	The geometry type: polygon, polyline, point, multipoint, multipatch, dimension, annotation.	String

Method Overview

Method	Explanation
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.

Methods

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.

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.

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.

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.

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.

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.

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.

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

Polygon example

Create a polyline feature class from scratch.

import arcpy

# A list of features and coordinate pairs
#
coordList = [[[1,2], [2,4], [3,7]],
            [[6,8], [5,7], [7,2], [9,5]]]

# Create empty Point and Array objects
#
point = arcpy.Point()
array = arcpy.Array()

# A list that will hold each of the Polygon objects 
# 
featureList = []

for feature in coordList:
    # For each coordinate pair, set the x,y properties and add to the 
    #  Array object.
    #
    for coordPair in feature:
        point.X = coordPair[0]
        point.Y = coordPair[1]
        array.add(point)

    # Add the first point of the array in to close off the polygon
    #
    array.add(array.getObject(0))

    # Create a Polygon object based on the array of points
    #
    polygon = arcpy.Polygon(array)

    # Clear the array for future use
    #
    array.removeAll()

    # Append to the list of Polygon objects
    #
    featureList.append(polygon)

# Create a copy of the Polygon objects, by using featureList as input to 
#  the CopyFeatures tool.
#
arcpy.CopyFeatures_management(featureList, "c:/geometry/polygons.shp")