Polyline (arcpy)

摘要

折线对象是由一个或多个路径定义的形状，其中路径是指一系列相连线段。

讨论

在许多地理处理工作流中，您可能需要使用坐标和几何信息运行特定操作，但不一定想经历创建新（临时）要素类、使用光标填充要素类、使用要素类，然后删除临时要素类的过程。可以使用几何对象替代输入和输出，从而使地理处理变得更简单。可以使用 Geometry、Multipoint、PointGeometry、Polygon 或 Polyline 类从头开始创建几何对象。

语法

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

参数	说明	数据类型
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. (默认值为 None)	SpatialReference
has_z	The Z state: True for geometry if Z is enabled and False if it is not. (默认值为 False)	Boolean
has_m	The M state: True for geometry if M is enabled and False if it is not. (默认值为 False)	Boolean

属性

属性	说明	数据类型
JSON (只读)	返回一个字符串形式的几何 JSON 制图表达。 提示: 通过 Python 的 json.loads 函数，返回的字符串可转换至字典。	String
WKB (只读)	返回 OGC 几何的熟知二进制 (WKB) 制图表达。 该存储类型将几何值表示为不间断的字节流形式。	Bytearray
WKT (只读)	返回 OGC 几何的熟知文本 (WKT) 制图表达。其将几何值表示为文本字符串。	String
area (只读)	面要素的面积。其他所有要素类型为空。	Double
centroid (只读)	如果质心位于要素之内或要素之上则为真；否则返回标注点。返回点对象。	Point
extent (读写)	几何范围。	Extent
firstPoint (只读)	第一个几何坐标点。	Point
hullRectangle (只读)	以空格分隔的凸包矩形坐标对的字符串。	String
isMultipart (只读)	如果此几何的部分数大于一，则为真。	Boolean
labelPoint (只读)	标注位置所在的点。标注点始终位于要素之内/之上。	Point
lastPoint (只读)	要素的最后一个坐标。	Point
length (只读)	线状要素的长度。点和多点要素类型为零。	Double
length3D (读写)	线状要素的 3D 长度。点和多点要素类型为零。	Double
partCount (只读)	要素几何部分的数目。	Integer
pointCount (只读)	要素的总点数。	Integer
spatialReference (只读)	几何的空间参考。	SpatialReference
trueCentroid (只读)	要素的重心。	Point
type (只读)	几何类型：面、折线、点、多点、多面体、尺寸或注记。	String

方法概述

方法	说明
boundary ()	构造几何边界。
buffer (distance)	在距几何的指定距离处构造一个面。
clip (envelope)	构造几何体与指定范围的交集。
contains (second_geometry)	Indicates if the base geometry contains the comparison geometry. contains is the opposite of within. 本图仅显示 True 关系。
convexHull ()	构造具有最小边界多边形的几何，以便所有外角均为凸角。
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. 本图仅显示 True 关系。
cut (cutter)	将该几何分割到剪切折线的左右两侧。 剪切折线或面时，会从其与剪切折线的相交处将其分割。每一段被分类为剪切线的左侧或右侧。该分类基于剪切线的方向。目标折线中不与剪切折线相交的部分将作为该输入折线结果的右侧部分返回。如果未对几何进行剪切，则左侧几何将为空 (None)。
difference (other)	构造一个几何体，该几何体仅由基础几何所特有、而其他几何所没有的区域组成。下图显示当红色多边形为源几何时的结果。
disjoint (second_geometry)	Indicates if the base and comparison geometries share no points in common. Two geometries intersect if disjoint returns False. 本图仅显示 True 关系。
distanceTo (other)	返回两个几何之间的最小距离。如果两个几何相交，则最小距离为 0。 两个几何必须具有相同的投影。
equals (second_geometry)	指示原几何和参照几何的 shape 类型是否相同并在平面中定义相同点集。这仅是 2D 的比较；已忽略 M 值和 Z 值。 本图仅显示 True 关系。
getArea ({type}, {units})	使用测量类型返回要素的面积。
getLength ({measurement_type}, {units})	使用测量类型返回要素的长度。
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)	构造作为两个输入几何交集的几何体。不同的维数可用于创建不同的 shape 类型。 对于同一 shape 类型的两个几何体，其交集为仅包含原始几何重叠区域的几何。 为了更快地获取结果，请在调用 intersect 类之前先测试两个几何体是否不相交。
measureOnLine (in_point, {as_percentage})	从此条线的起点向 in_point 返回一个测量值。
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. 本图仅显示 True 关系。
positionAlongLine (value, {use_percentage})	返回线上距线起点指定距离处的点。
projectAs (spatial_reference, {transformation_name})	定义几何投影，并应用相应的地理变换。 要进行投影，几何体需要具有一个空间参考且不具有 UnknownCoordinateSystem。传递到该方法的新空间参考系统参数定义了一个输出坐标系。如果任一空间参考未知，坐标将不会发生更改。ProjectAs 方法并不更改 Z 值和测量值。
queryPointAndDistance (in_point, {as_percentage})	在折线上找到离 in_point 最近的点，并确定这两点间的距离。同时返回关于 in_point 位于线的哪一侧以及最近点沿线的距离。
snapToLine (in_point)	基于以该几何作为捕捉目标的 in_point 返回一个新点。
symmetricDifference (other)	构造一个几何体，该几何体由两个几何的并集减去其交集所形成。 两个输入几何必须为同一 shape 类型。
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. 本图仅显示 True 关系。
union (other)	构造一个几何体，该几何体是输入几何的并集。 要合并的两个几何必须为同一 shape 类型。
within (second_geometry)	Indicates if the base geometry is within the comparison geometry. within is the opposite operator of contains. 本图仅显示 True 关系。

方法

boundary ()

返回值

数据类型	说明
Object	面的边界为折线。折线的边界为多点，与线的端点相对应。点或多点的边界为空点或多点。

buffer (distance)

参数	说明	数据类型
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

返回值

数据类型	说明
Polygon	缓冲的面几何。

clip (envelope)

参数	说明	数据类型
envelope	An extent object used to define the clip extent.	Extent

返回值

数据类型	说明
Object	将输出几何体按指定范围进行裁剪。

contains (second_geometry)

参数	说明	数据类型
second_geometry	A second geometry.	Object

返回值

数据类型	说明
Boolean	A return Boolean value of True indicates this geometry contains the second geometry.

convexHull ()

返回值

数据类型	说明
Object	生成的几何。单个点的凸包为该点本身。

crosses (second_geometry)

参数	说明	数据类型
second_geometry	A second geometry.	Object

返回值

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

cut (cutter)

参数	说明	数据类型
cutter	The cutting polyline geometry.	PolyLine

返回值

数据类型	说明
Geometry	包含两个几何的列表。

difference (other)

参数	说明	数据类型
other	A second geometry.	Object

返回值

数据类型	说明
Object	生成的几何。

disjoint (second_geometry)

参数	说明	数据类型
second_geometry	A second geometry.	Object

返回值

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

distanceTo (other)

参数	说明	数据类型
other	A second geometry.	Object

返回值

数据类型	说明
Double	两个几何之间的距离。

equals (second_geometry)

参数	说明	数据类型
second_geometry	A second geometry.	Object

返回值

数据类型	说明
Boolean	返回布尔值为 True 表示两个几何的 shape 类型相同并在平面中定义了相同点集。

getArea ({type}, {units})

参数	说明	数据类型
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 measurements 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. (默认值为 GEODESIC)	String
units	The units in which the area will be calculated. Areal unit of measure keywords: ACRES | ARES | HECTARES | SQUARECENTIMETERS | SQUAREDECIMETERS | SQUAREINCHES | SQUAREFEET | SQUAREKILOMETERS | SQUAREMETERS | SQUAREMILES | SQUAREMILLIMETERS | SQUAREYARDS	String

返回值

数据类型	说明
Double	要素的面积。 默认情况下，在投影坐标系中，将采用坐标系的单位返回面积，在地理坐标系中，将以平方米为单位返回面积。

getLength ({measurement_type}, {units})

参数	说明	数据类型
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 measurements 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. (默认值为 GEODESIC)	String
units	The units in which the length will be calculated. Linear unit of measure keywords: CENTIMETERS | DECIMETERS | FEET | INCHES | KILOMETERS | METERS | MILES | MILLIMETERS | NAUTICALMILES | YARDS	String

返回值

数据类型	说明
Double	要素的长度。 默认情况下，在投影坐标系中，将采用坐标系的单位返回长度，在地理坐标系中，将以米为单位返回长度。

getPart ({index})

参数	说明	数据类型
index	The index position of the geometry.	Integer

返回值

数据类型	说明
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)

参数	说明	数据类型
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

返回值

数据类型	说明
Object	作为两个输入几何体的交集的新几何体（点、多点、折线或面）。

measureOnLine (in_point, {as_percentage})

参数	说明	数据类型
in_point	A point (PointGeometry or Point) that is used to measure from the start point of the polyline.	PointGeometry
as_percentage	If False, the measure will be returned as a distance; if True, the measure will be returned as a percentage. (默认值为 False)	Boolean

返回值

数据类型	说明
Double	一个距离或百分比。

overlaps (second_geometry)

参数	说明	数据类型
second_geometry	A second geometry.	Object

返回值

数据类型	说明
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})

参数	说明	数据类型
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. For percentages, the value should be expressed as a double from 0.0 (0%) to 1.0 (100%). (默认值为 False)	Boolean

返回值

数据类型	说明
PointGeometry	线上距线起点指定距离的点。

projectAs (spatial_reference, {transformation_name})

参数	说明	数据类型
spatial_reference	The new spatial reference. This can be a SpatialReference object or the coordinate system name.	SpatialReference
transformation_name	The geotransformation name.	String

返回值

数据类型	说明
Object	经投影的几何。

queryPointAndDistance (in_point, {as_percentage})

参数	说明	数据类型
in_point	The input point (PointGeometry or Point).	PointGeometry
as_percentage	If False, the measure will be returned as a distance; if True, the measure will be returned as a percentage. (默认值为 False)	Boolean

返回值

数据类型	说明
tuple	返回包含以下信息的一个元组： 用来表示折线上距 in_point 最近的点的 PointGeometry。 线的起点与线上所返回的点之间的距离。 线和 in_point 之间的最小距离。 用来表示 in_point 是否位于线的右侧的布尔值。线的方向决定左右两侧。

snapToLine (in_point)

参数	说明	数据类型
in_point	A point (PointGeometry or Point) to be snapped to the line.	PointGeometry

返回值

数据类型	说明
PointGeometry	捕捉到的点。

symmetricDifference (other)

参数	说明	数据类型
other	A second geometry.	Object

返回值

数据类型	说明
Object	生成的几何。

touches (second_geometry)

参数	说明	数据类型
second_geometry	A second geometry.	Object

返回值

数据类型	说明
Boolean	A return Boolean value of True indicates the boundaries of the geometries intersect.

union (other)

参数	说明	数据类型
other	A second geometry.	Object

返回值

数据类型	说明
Object	生成的几何。

within (second_geometry)

参数	说明	数据类型
second_geometry	A second geometry.	Object

返回值

数据类型	说明
Boolean	A return Boolean value of True indicates this geometry is contained within the second geometry.

代码实例

折线示例

从头开始创建折线要素类。

import arcpy

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

# A list that will hold each of the Polyline objects
features = []

for feature in feature_info:
    # Create a Polyline object based on the array of points
    # Append to the list of Polyline objects
    features.append(
        arcpy.Polyline(
            arcpy.Array([arcpy.Point(*coords) for coords in feature])))

# Persist a copy of the Polyline objects using CopyFeatures
arcpy.CopyFeatures_management(features, "c:/geometry/polylines.shp")