VfTable (arcpy.sa)

Zusammenfassung

Defines the relationship between the vertical cost factor and the vertical relative moving angle with a vertical-factor graph identifying the vertical factor specified by a table file.

Diskussion

The VfTable object is used in the Spatial Analyst tools Path Distance, Path Distance Allocation, and Path Distance Back Link.

The vertical factor (VF) object defines the relationship between the vertical cost factor and the vertical relative moving angle (VRMA).

VF defines the vertical difficulty encountered in moving from one cell to the next.

VRMA identifies the slope angle between the FROM or processing cell and the TO cell.

Syntax

VfTable (inTable)

Parameter	Erläuterung	Datentyp
inTable	The inTable is an ASCII file with two columns on each line. The first column identifies the VRMA in degrees, and the second, the VF. Each line specifies a point. Two consecutive points produce a line segment in the VRMA-VF coordinate system. The VRMAs must be input in ascending order. The VF factor for any VRMA less than the first (lowest) input value or larger than the final (largest) input will be set to infinity. An infinite VF is represented by -1 in the ASCII table.	File

Eigenschaften

Eigenschaft	Erläuterung	Datentyp
inTable (Lesen und schreiben)	The inTable is an ASCII file with two columns on each line. The first column identifies the VRMA in degrees, and the second, the VF. Each line specifies a point. Two consecutive points produce a line segment in the VRMA-VF coordinate system. The VRMAs must be input in ascending order. The VF factor for any VRMA less than the first (lowest) input value or larger than the final (largest) input will be set to infinity. An infinite VF is represented by -1 in the ASCII table.	String

Codebeispiel

VfTable example 1 (Python window)

Demonstrates how to create a VfTable class and use it in the PathDistance tool within the Python window.

import arcpy
from arcpy import env
from arcpy.sa import *
env.workspace = "C:/sapyexamples/data"
myVerticalFactor = VfTable("vffile.txt")
outPathDist = PathDistance("source.shp", "costraster", "", "", "", "",
                           myVerticalFactor)
outPathDist.save("C:/sapyexamples/output/pathdistvft")

VfTable example 2 (stand-alone script)

Performs a PathDistance analysis using the VfTable class.

# Name: VfTable_Ex_02.py
# Description: Uses the VfTable object to execute the PathDistance 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
inSourceData = "source.shp"
inCostRaster = "costraster"

# Create the VfTable Object
inTable = "vffile.txt"
myVerticalFactor = VfTable(inTable)

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

# Execute PathDistance
outPathDist = PathDistance(inSourceData, inCostRaster, "", "", "", "",
                           myVerticalFactor)

# Save the output 
outPathDist.save("C:/sapyexamples/output/pathdistvft2")