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})
ParámetroExplicaciónTipo 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

PropiedadExplicaciónTipo de datos
JSON
(Sólo lectura)

Returns a JSON representation of the geometry as a string.

SugerenciaSugerencia:

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

MétodoExplicación
boundary ()

Constructs the boundary of the geometry.

Boundary operator
buffer (distance)

Constructs a polygon at a specified distance from the geometry.

Buffer operator
clip (envelope)

Constructs the intersection of the geometry and the specified extent.

Clip operator
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.

Possible contains relationships
convexHull ()

Constructs the geometry that is the minimal bounding polygon such that all outer angles are convex.

ConvexHull operator
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.

Possible crosses relationships
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.

Difference operator
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.

Possible disjoint relationships
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.

Possible equals relationships
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.

Intersect operator

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.

Possible overlaps relationships
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.

symmetricDifference operator
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.

Possible touches relationships
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.

Union operator
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.

Possible within relationships

Métodos

boundary ()
Valor de retorno
Tipo de datosExplicación
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)
ParámetroExplicaciónTipo 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 datosExplicación
Polygon

The buffered polygon geometry.

clip (envelope)
ParámetroExplicaciónTipo de datos
envelope

An extent object used to define the clip extent.

Extent
Valor de retorno
Tipo de datosExplicación
Object

An output geometry clipped to the specified extent.

contains (second_geometry)
ParámetroExplicaciónTipo de datos
second_geometry

A second geometry.

Object
Valor de retorno
Tipo de datosExplicación
Boolean

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

convexHull ()
Valor de retorno
Tipo de datosExplicación
Object

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

crosses (second_geometry)
ParámetroExplicaciónTipo de datos
second_geometry

A second geometry.

Object
Valor de retorno
Tipo de datosExplicación
Boolean

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

difference (other)
ParámetroExplicaciónTipo de datos
other

A second geometry.

Object
Valor de retorno
Tipo de datosExplicación
Object

The resulting geometry.

disjoint (second_geometry)
ParámetroExplicaciónTipo de datos
second_geometry

A second geometry.

Object
Valor de retorno
Tipo de datosExplicación
Boolean

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

distanceTo (other)
ParámetroExplicaciónTipo de datos
other

A second geometry.

Object
Valor de retorno
Tipo de datosExplicación
Double

The distance between the two geometries.

equals (second_geometry)
ParámetroExplicaciónTipo de datos
second_geometry

A second geometry.

Object
Valor de retorno
Tipo de datosExplicación
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)
ParámetroExplicaciónTipo 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.

  • GEODESICThe 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_ELLIPTICThe 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.
  • LOXODROMEA 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.
  • PLANARPlanar 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_SHAPEThis 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 datosExplicación
Double

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

getLength (measurement_type)
ParámetroExplicaciónTipo 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.

  • GEODESICThe 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_ELLIPTICThe 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.
  • LOXODROMEA 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.
  • PLANARPlanar 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_SHAPEThis 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 datosExplicación
Double

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

getPart ({index})
ParámetroExplicaciónTipo de datos
index

The index position of the geometry.

Integer
Valor de retorno
Tipo de datosExplicación
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)
ParámetroExplicaciónTipo de datos
other

The second geometry.

Object
dimension

The topological dimension (shape type) of the resulting geometry.

  • 1A zero-dimensional geometry (point or multipoint).
  • 2A one-dimensional geometry (polyline).
  • 4A two-dimensional geometry (polygon).
Integer
Valor de retorno
Tipo de datosExplicación
Object

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

overlaps (second_geometry)
ParámetroExplicaciónTipo de datos
second_geometry

A second geometry.

Object
Valor de retorno
Tipo de datosExplicación
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})
ParámetroExplicaciónTipo 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 datosExplicación
PointGeometry

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

projectAs (spatial_reference, {transformation_name})
ParámetroExplicaciónTipo 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 datosExplicación
Object

The projected geometry.

symmetricDifference (other)
ParámetroExplicaciónTipo de datos
other

A second geometry.

Object
Valor de retorno
Tipo de datosExplicación
Object

The resulting geometry.

touches (second_geometry)
ParámetroExplicaciónTipo de datos
second_geometry

A second geometry.

Object
Valor de retorno
Tipo de datosExplicación
Boolean

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

union (other)
ParámetroExplicaciónTipo de datos
other

A second geometry.

Object
Valor de retorno
Tipo de datosExplicación
Object

The resulting geometry.

within (second_geometry)
ParámetroExplicaciónTipo de datos
second_geometry

A second geometry.

Object
Valor de retorno
Tipo de datosExplicación
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")

Temas relacionados

9/11/2013