FuzzyNear

Summary

Defines a fuzzy membership function around a specific value which is defined by a user-defined midpoint (which is assigned a membership of 1), with a defined spread decreasing to zero.

Discussion

The tool that uses the FuzzyNear object: Fuzzy Membership.

The equation for the fuzzy Near function is:

The inputs to the equation are f1, the spread, and f2, the midpoint. Increasing the spread causes the fuzzy membership curve to become steeper.

The Near function is useful if the membership is near a specific value.

The input values can be either integer or floating-point positive values.

The Near function is similar to the Gaussian fuzzy membership function except the Near function has a more narrow spread.

Variations of the fuzzy Near membership function.

Syntax

FuzzyNear (midpoint, spread)

Parameter	Explanation	Data Type
midpoint	The user-defined value with a fuzzy membership of 1. The default is the midpoint of the range of values of the input raster.	Double
spread	Defines the spread of the Near function. The spread generally ranges from 0.001 to 1 with the larger the value results in a steeper distribution from the midpoint. (The default value is 0.1)	Double

Properties

Property	Explanation	Data Type
midpoint (Read and Write)	The user-defined value defining the midpoint for the membership function.	Double
spread (Read and Write)	Defines the spread of the membership function. The larger the value results in a steeper distribution from the midpoint.	Double

Code Sample

FuzzyNear example 1 (Python window)

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

import arcpy
from arcpy.sa import *
from arcpy import env
env.workspace = "c:/sapyexamples/data"
outFzyMember = FuzzyMembership("as_std", FuzzyGaussian(9, 0.1))
outFzyMember.save("c:/sapyexamples/fzynear")

FuzzyNear example 2 (stand-alone script)

Performs a FuzzyMembership using the FuzzyNear class.

# Name: FuzzyNear_Ex_02.py
# Description: Scales input raster data into values ranging from zero to one
#     indicating the strength of a membership in a set. 
# 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 = "as_std"

# Create the FuzzyNear algorithm object
midpoint = 11
spread = 0.2
myFuzzyAlgorithm = FuzzyNear(midpoint, spread)

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

# Execute FuzzyMembership
outFuzzyMember = FuzzyMembership(inRaster, myFuzzyAlgorithm)

# Save the output
outFuzzyMember.save("c:/sapyexamples/fzynear2")