Polyline (arcpy)

Récapitulatif

A Polyline object is a shape defined by one or more paths, in which a path is a series of connected segments.

Discussion

Dans de nombreux workflows de géotraitement, vous devez éventuellement exécuter une opération spécifique à l'aide d'informations sur les coordonnées et la géométrie, sans vouloir nécessairement créer une nouvelle classe d'entités (temporaire), la remplir avec des curseurs, l'utiliser, puis la supprimer. Les objets géométrie peuvent alors être utilisés en entrée et en sortie afin de simplifier le géotraitement. Les objets géométrie peuvent être entièrement créés à l'aide des classes Geometry, Multipoint, PointGeometry, Polygon ou Polyline.

Syntaxe

Polyline (inputs, {spatial_reference}, {has_z}, {has_m})
ParamètreExplicationType de données
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.

(La valeur par défaut est None)

SpatialReference
has_z

The Z state: True for geometry if Z is enabled and False if it is not.

(La valeur par défaut est False)

Boolean
has_m

The M state: True for geometry if M is enabled and False if it is not.

(La valeur par défaut est False)

Boolean

Propriétés

PropriétéExplicationType de données
JSON
(Lecture seule)

Returns a JSON representation of the geometry as a string.

AstuceAstuce:

The returned string can be converted to a dictionary by Python's eval function.

String
WKB
(Lecture seule)

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
(Lecture seule)

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
(Lecture seule)

The area of a polygon feature. Empty for all other feature types.

Double
centroid
(Lecture seule)

The true centroid if it is within or on the feature; otherwise, the label point is returned. Returns a point object.

Point
extent
(Lecture seule)

The extent of the geometry.

Extent
firstPoint
(Lecture seule)

The first coordinate point of the geometry.

Point
hullRectangle
(Lecture seule)

A space-delimited string of the coordinate pairs of the convex hull rectangle.

String
isMultipart
(Lecture seule)

True, if the number of parts for this geometry is more than one.

Boolean
labelPoint
(Lecture seule)

The point at which the label is located. The labelPoint is always located within or on a feature.

Point
lastPoint
(Lecture seule)

The last coordinate of the feature.

Point
length
(Lecture seule)

The length of the linear feature. Zero for point and multipoint feature types.

Double
length3D
(Lecture/écriture)

The 3D length of the linear feature. Zero for point and multipoint feature types.

Double
partCount
(Lecture seule)

The number of geometry parts for the feature.

Integer
pointCount
(Lecture seule)

The total number of points for the feature.

Integer
trueCentroid
(Lecture seule)

The center of gravity for a feature.

Point
type
(Lecture seule)

The geometry type: polygon, polyline, point, multipoint, multipatch, dimension, or annotation.

String

Vue d'ensemble des méthodes

MéthodeExplication
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)

Indique si la géométrie de base contient la géométrie de comparaison.

contains est le contraire de within.

Only True relationships are shown in this illustration.

Relations contains possibles
convexHull ()

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

ConvexHull operator
crosses (second_geometry)

Indique si les deux géométries s'intersectent dans une géométrie de type de forme inférieure.

Deux polylignes se croisent si elles partagent uniquement des points, dont au moins un n'est pas une extrémité. Une polyligne et un polygone se croisent s'ils partagent une polyligne ou un point (pour une ligne verticale) à l'intérieur du polygone qui n'est pas équivalent à la polyligne entière.

Only True relationships are shown in this illustration.

Relations crosses possibles
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)

Indique si la géométrie de base et la géométrie de comparaison n'ont aucun point en commun.

Deux géométries s'intersectent si la propriété disjoint renvoie False.

Only True relationships are shown in this illustration.

Relations disjoint possibles
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)

Indique si l'intersection des deux géométries possède le même type de forme que l'une des géométries en entrée et qu'elle n'est pas équivalente à l'une des géométries en entrée.

Only True relationships are shown in this illustration.

Relations overlaps possibles
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)

Indique si les limites des géométries s'intersectent.

Deux géométries se touchent lorsque l'intersection des géométries n'est pas vide, mais que l'intersection de leurs intérieurs est vide. Par exemple, un point touche une polyligne uniquement s'il coïncide avec l'une des extrémités de la polyligne.

Only True relationships are shown in this illustration.

Relations touches possibles
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)

Indique si la géométrie de base se trouve dans la géométrie de comparaison.

within est l'opérateur contraire de contains.

Only True relationships are shown in this illustration.

Relations within possibles

Méthodes

boundary ()
Valeur renvoyée
Type de donnéesExplication
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)
ParamètreExplicationType de données
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
Valeur renvoyée
Type de donnéesExplication
Polygon

The buffered polygon geometry.

clip (envelope)
ParamètreExplicationType de données
envelope

An extent object used to define the clip extent.

Extent
Valeur renvoyée
Type de donnéesExplication
Object

An output geometry clipped to the specified extent.

contains (second_geometry)
ParamètreExplicationType de données
second_geometry

A second geometry.

Object
Valeur renvoyée
Type de donnéesExplication
Boolean

Une valeur booléenne renvoyée True indique que cette géométrie contient la deuxième géométrie.

convexHull ()
Valeur renvoyée
Type de donnéesExplication
Object

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

crosses (second_geometry)
ParamètreExplicationType de données
second_geometry

A second geometry.

Object
Valeur renvoyée
Type de donnéesExplication
Boolean

Une valeur booléenne renvoyée True indique que les deux géométries s'intersectent dans une géométrie de type de forme inférieure.

difference (other)
ParamètreExplicationType de données
other

A second geometry.

Object
Valeur renvoyée
Type de donnéesExplication
Object

The resulting geometry.

disjoint (second_geometry)
ParamètreExplicationType de données
second_geometry

A second geometry.

Object
Valeur renvoyée
Type de donnéesExplication
Boolean

Une valeur booléenne renvoyée True indique que les deux géométries n'ont aucun point en commun.

distanceTo (other)
ParamètreExplicationType de données
other

A second geometry.

Object
Valeur renvoyée
Type de donnéesExplication
Double

The distance between the two geometries.

equals (second_geometry)
ParamètreExplicationType de données
second_geometry

A second geometry.

Object
Valeur renvoyée
Type de donnéesExplication
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)
ParamètreExplicationType de données
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
Valeur renvoyée
Type de donnéesExplication
Double

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

getLength (measurement_type)
ParamètreExplicationType de données
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
Valeur renvoyée
Type de donnéesExplication
Double

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

getPart ({index})
ParamètreExplicationType de données
index

The index position of the geometry.

Integer
Valeur renvoyée
Type de donnéesExplication
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)
ParamètreExplicationType de données
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
Valeur renvoyée
Type de donnéesExplication
Object

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

overlaps (second_geometry)
ParamètreExplicationType de données
second_geometry

A second geometry.

Object
Valeur renvoyée
Type de donnéesExplication
Boolean

Une valeur booléenne renvoyée True indique que l'intersection des deux géométries a la même dimension que l'une des géométries en entrée.

positionAlongLine (value, {use_percentage})
ParamètreExplicationType de données
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.

(La valeur par défaut est False)

Boolean
Valeur renvoyée
Type de donnéesExplication
PointGeometry

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

projectAs (spatial_reference, {transformation_name})
ParamètreExplicationType de données
spatial_reference

The new spatial reference. This can be a SpatialReference object or the coordinate system name.

SpatialReference
transformation_name

The geotransformation name.

String
Valeur renvoyée
Type de donnéesExplication
Object

The projected geometry.

symmetricDifference (other)
ParamètreExplicationType de données
other

A second geometry.

Object
Valeur renvoyée
Type de donnéesExplication
Object

The resulting geometry.

touches (second_geometry)
ParamètreExplicationType de données
second_geometry

A second geometry.

Object
Valeur renvoyée
Type de donnéesExplication
Boolean

Une valeur booléenne renvoyée True indique que les limites des géométries s'intersectent.

union (other)
ParamètreExplicationType de données
other

A second geometry.

Object
Valeur renvoyée
Type de donnéesExplication
Object

The resulting geometry.

within (second_geometry)
ParamètreExplicationType de données
second_geometry

A second geometry.

Object
Valeur renvoyée
Type de donnéesExplication
Boolean

Une valeur booléenne renvoyée True indique que cette géométrie est contenue dans la deuxième géométrie.

Exemple de code

Polyline 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 Polyline 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)

    # Create a Polyline object based on the array of points
    #
    polyline = arcpy.Polyline(array)

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

    # Append to the list of Polyline objects
    #
    featureList.append(polyline)

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

Thèmes connexes

9/12/2013