NbrWedge (arcpy.sa)

摘要

定义通过指定半径和两个角度（以地图单位或像元数为单位）而创建的楔形邻域。

插图

FocalStatistics 函数的 NbrWedge 邻域示例

BlockStatistics 函数的 NbrWedge 邻域示例

讨论

使用楔形邻域对象的工具包括：块统计、焦点统计、点统计和点密度。

楔形由半径、起始角度、终止角度及单位进行指定。楔形按逆时针方向从起始角延伸到终止角。角度为算术度（基于 x 轴正向按逆时针方向进行测量）。也可使用负角度。

半径用像元单位或地图单位标识并且沿着垂直于 x 轴或 y 轴的方向进行测量。采用地图单位指定半径时，会将其转换为以像元为单位的半径。所得的以像元为单位的半径会生成一个区域，该区域能够近似地表示出使用原始的地图单位为半径时计算的区域。中心位于楔形内的所有像元都将包括在邻域的处理范围内。

语法

NbrWedge ({radius}, {startAngle}, {endAngle}, {units})

参数	说明	数据类型
radius	The radius is the distance from the corner of the wedge to the outer limit of the wedge. The radius is an integer or floating-point value. (默认值为 3)	Double
startAngle	The startAngle is an integer or floating-point value from 0 to 360. The start angle is measured counterclockwise from the positive x-axis (3:00 on a clock) to the closest edge of the wedge. (默认值为 0)	Double
endAngle	The endAngle is an integer or floating-point value from 0 to 360. The end angle is measured counterclockwise from the positive x-axis (3:00 on a clock) to the outer edge of the wedge. (默认值为 90)	Double
units	Defines the units of the neighborhood. CELL —The unit of measurement is in cells. MAP —The units are in map coordinates. (默认值为 CELL)	String

属性

属性	说明	数据类型
radius (读写)	The radius is the distance from the corner of the wedge to the outer limit of the wedge. The radius is an integer or floating-point value.	Double
startAngle (读写)	The startAngle is a value from 0 to 360. It can be integer or floating-point. The start angle is measured counterclockwise from the positive x-axis (3:00 on a clock) to the closest edge of the wedge.	Double
endAngle (读写)	The endAngle is a value ranging from 0 to 360. It can be integer or floating-point. The endAngle is measured counterclockwise from the positive x-axis (3:00 on a clock) to the outer edge of the wedge.	Double
units (读写)	Defines the units of the neighborhood.	String

代码实例

NbrWedge 示例 1（Python 窗口）

演示如何创建 NbrWedge 类以及如何在 Python 窗口的 BlockStatistics 工具中使用该类。

import arcpy
from arcpy import env
from arcpy.sa import *
env.workspace = "C:/sapyexamples/data"
outNbrWedge = BlockStatistics("block", NbrWedge(5, 10.5, 40, "MAP"))
outNbrWedge.save("C:/sapyexamples/output/blstatsnbrw2")

NbrWedge 示例 2（独立脚本）

使用 NbrWedge 类执行 BlockStatistics 工具。

# Name: NbrWedge_Ex_02.py
# Description: Uses the NbrWedge object to execute BlockStatistics tool
# Requirements: Spatial Analyst Extension

# Import system modules
import arcpy
from arcpy import env
from arcpy.sa import *

# Set environment settings
env.workspace = "C:/sapyexamples/data"

# Set local variables
inRaster = "block"

# Create the Neighborhood Object
radius = 5
startAngle = 5
endAngle = 10

myNbrWedge = NbrWedge(radius, startAngle, endAngle, "")

# Check out the ArcGIS Spatial Analyst extension license
arcpy.CheckOutExtension("Spatial")

# Execute BlockStatistics
outBlkStats =  BlockStatistics(inRaster, myNbrWedge, "MINIMUM", "DATA")

# Save the output 
outBlkStats.save("C:/sapyexamples/output/blkst_wedge4")