Polygon (arcpy)

Resumen

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

Debate

En muchos flujos de trabajo de geoprocesamiento, puede que necesite ejecutar una operación concreta utilizando información de coordenadas y geometría, pero que no necesariamente desee pasar por el proceso de crear una nueva clase de entidad (temporal), llenar la clase de entidad con cursores, utilizar la clase de entidad y, a continuación, eliminar la clase de entidad temporal. En su lugar, puede utilizar objetos de geometría tanto para la entrada como para la salida, para simplificar el geoprocesamiento. Los objetos de geometría se pueden crear utilizando clases Geometry, Multipoint, PointGeometry, Polygon o Polyline .

Sintaxis

Polygon (inputs, {spatial_reference}, {has_z}, {has_m})

Parámetro	Explicación	Tipo de datos
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. (El valor predeterminado es None)	SpatialReference
has_z	The Z state: True for geometry if Z is enabled and False if it is not. (El valor predeterminado es False)	Boolean
has_m	The M state: True for geometry if M is enabled and False if it is not. (El valor predeterminado es False)	Boolean

Propiedades

Propiedad	Explicación	Tipo de datos
JSON (Sólo lectura)	Returns a JSON representation of the geometry as a string. Sugerencia: The returned string can be converted to a dictionary by Python's eval function.	String
WKB (Sólo lectura)	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 (Sólo lectura)	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 (Sólo lectura)	The area of a polygon feature. Empty for all other feature types.	Double
centroid (Sólo lectura)	The true centroid if it is within or on the feature; otherwise, the label point is returned. Returns a point object.	Point
extent (Sólo lectura)	The extent of the geometry.	Extent
firstPoint (Sólo lectura)	The first coordinate point of the geometry.	Point
hullRectangle (Sólo lectura)	A space-delimited string of the coordinate pairs of the convex hull rectangle.	String
isMultipart (Sólo lectura)	True, if the number of parts for this geometry is more than one.	Boolean
labelPoint (Sólo lectura)	The point at which the label is located. The labelPoint is always located within or on a feature.	Point
lastPoint (Sólo lectura)	The last coordinate of the feature.	Point
length (Sólo lectura)	The length of the linear feature. Zero for point and multipoint feature types.	Double
length3D (Lectura y escritura)	The 3D length of the linear feature. Zero for point and multipoint feature types.	Double
partCount (Sólo lectura)	The number of geometry parts for the feature.	Integer
pointCount (Sólo lectura)	The total number of points for the feature.	Integer
trueCentroid (Sólo lectura)	The center of gravity for a feature.	Point
type (Sólo lectura)	The geometry type: polygon, polyline, point, multipoint, multipatch, dimension, or annotation.	String

Descripción general de los métodos

Método	Explicación
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.

Métodos

boundary ()

Valor de retorno

Tipo de datos	Explicación
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)

Parámetro	Explicación	Tipo de datos
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

Valor de retorno

Tipo de datos	Explicación
Polygon	The buffered polygon geometry.

clip (envelope)

Parámetro	Explicación	Tipo de datos
envelope	An extent object used to define the clip extent.	Extent

Valor de retorno

Tipo de datos	Explicación
Object	An output geometry clipped to the specified extent.

contains (second_geometry)

Parámetro	Explicación	Tipo de datos
second_geometry	A second geometry.	Object

Valor de retorno

Tipo de datos	Explicación
Boolean	A return Boolean value of True indicates this geometry contains the second geometry.

convexHull ()

Valor de retorno

Tipo de datos	Explicación
Object	The resulting geometry. The convex hull of a single point is the point itself.

crosses (second_geometry)

Parámetro	Explicación	Tipo de datos
second_geometry	A second geometry.	Object

Valor de retorno

Tipo de datos	Explicación
Boolean	A return Boolean value of True indicates the two geometries intersect in a geometry of a lesser shape type.

difference (other)

Parámetro	Explicación	Tipo de datos
other	A second geometry.	Object

Valor de retorno

Tipo de datos	Explicación
Object	The resulting geometry.

disjoint (second_geometry)

Parámetro	Explicación	Tipo de datos
second_geometry	A second geometry.	Object

Valor de retorno

Tipo de datos	Explicación
Boolean	A return Boolean value of True indicates that the two geometries share no points in common.

distanceTo (other)

Parámetro	Explicación	Tipo de datos
other	A second geometry.	Object

Valor de retorno

Tipo de datos	Explicación
Double	The distance between the two geometries.

equals (second_geometry)

Parámetro	Explicación	Tipo de datos
second_geometry	A second geometry.	Object

Valor de retorno

Tipo de datos	Explicación
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)

Parámetro	Explicación	Tipo de datos
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

Valor de retorno

Tipo de datos	Explicación
Double	The area of the feature. Areas are always returned in square meters.

getLength (measurement_type)

Parámetro	Explicación	Tipo de datos
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

Valor de retorno

Tipo de datos	Explicación
Double	The length of the linear feature. Lengths are always returned in meters.

getPart ({index})

Parámetro	Explicación	Tipo de datos
index	The index position of the geometry.	Integer

Valor de retorno

Tipo de datos	Explicación
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)

Parámetro	Explicación	Tipo de datos
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

Valor de retorno

Tipo de datos	Explicación
Object	A new geometry (point, multipoint, polyline, or polygon) that is the geometric intersection of the two input geometries.

overlaps (second_geometry)

Parámetro	Explicación	Tipo de datos
second_geometry	A second geometry.	Object

Valor de retorno

Tipo de datos	Explicación
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})

Parámetro	Explicación	Tipo de datos
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. (El valor predeterminado es False)	Boolean

Valor de retorno

Tipo de datos	Explicación
PointGeometry	The point on the line at a specified distance from the beginning of the line.

projectAs (spatial_reference, {transformation_name})

Parámetro	Explicación	Tipo de datos
spatial_reference	The new spatial reference. This can be a SpatialReference object or the coordinate system name.	SpatialReference
transformation_name	The geotransformation name.	String

Valor de retorno

Tipo de datos	Explicación
Object	The projected geometry.

symmetricDifference (other)

Parámetro	Explicación	Tipo de datos
other	A second geometry.	Object

Valor de retorno

Tipo de datos	Explicación
Object	The resulting geometry.

touches (second_geometry)

Parámetro	Explicación	Tipo de datos
second_geometry	A second geometry.	Object

Valor de retorno

Tipo de datos	Explicación
Boolean	A return Boolean value of True indicates the boundaries of the geometries intersect.

union (other)

Parámetro	Explicación	Tipo de datos
other	A second geometry.	Object

Valor de retorno

Tipo de datos	Explicación
Object	The resulting geometry.

within (second_geometry)

Parámetro	Explicación	Tipo de datos
second_geometry	A second geometry.	Object

Valor de retorno

Tipo de datos	Explicación
Boolean	A return Boolean value of True indicates this geometry is contained within the second geometry.

Ejemplo de código

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")