TfMSSmall

Summary

Defines an MSSmall transformation function which is determined from the mean multiplier and standard deviation multiplier shape–controlling parameters as well as the lower and upper threshold that identify the range within which to apply the function.

Learn more about how the parameters affect this transformation function

Discussion

The tool that uses the TfMSSmall object is Rescale by Function.

Where \(x\) is the input value, there are two equations for the MSSmall function, depending on the product of \(a * m\):

If \(x > a * m\):

\(f(x) = (b * s) \space / \space (x - (a * m) + (b * s))\)
- where:
  
  \(x\) is the input value
  
  \(m\) is the mean
  
  \(s\) is the standard deviation
  
  \(a\) is a multiplier of the mean
  
  \(b\) is a multiplier of the standard deviation
  
  The \(a\) and \(b\) multipliers are input parameters.
If \(x <= a * m\):

\(f(x) = 0\)

The function values range from 0 to 1, which are then transformed to the evaluation scale.

The MSSmall function is useful when the small input values are preferred and they should receive the higher output evaluation values.

The result from the MSSmall transformation function can be similar to that of the Small transformation function, depending on how the multipliers of the mean and standard deviation are defined.

Syntax

TfMSSmall({meanMultiplier}, {STDMultiplier}, {lowerThreshold}, {valueBelowThreshold}, {upperThreshold}, {valueAboveThreshold})

Name	Explanation	Data type
meanMultiplier (Optional)	The multiplier for the mean of the input values in the MSSmall function equation. The `meanMultiplier` must be greater than 0. The default value is 1.0.	Double
STDMultiplier (Optional)	The multiplier for the standard deviation of the input values in the MSSmall function equation. The `STDMultiplier` must be greater than 0. The default value is 1.0.	Double
lowerThreshold (Optional)	Defines the starting value at which to begin applying the specified transformation function. The input value corresponding to the `lowerThreshold` is assigned to the `fromScale` evaluation scale value on the output raster. Input values below the `lowerThreshold` are assigned to the `valueBelowThreshold` and are not considered in the function value range. The `lowerThreshold` must be less than the `upperThreshold`. The default value is None.	Double
valueBelowThreshold (Optional)	A value to assign output cell locations with input values below the `lowerThreshold`. The value for `valueBelowThreshold` can be float, integer, or NoData. In the tool dialog box, no quotation marks are used around NoData; however, quotation marks are required around "NoData" when scripting. The default value is None.	Variant
upperThreshold (Optional)	Defines the ending value at which to stop applying the specified transformation function. The input value corresponding to the `upperThreshold` is assigned to the `toScale` evaluation scale value on the output raster. Input values above the `upperThreshold` are assigned to the `valueAboveThreshold` and are not considered in the function value range. The `lowerThreshold` must be less than the `upperThreshold`. The default value is None.	Double
valueAboveThreshold (Optional)	A value to assign output cell locations with input values above the `upperThreshold`. The value for `valueAboveThreshold` can be float, integer, or NoData. In the tool dialog box, no quotation marks are used around NoData; however, quotation marks are required around "NoData" when scripting. The default value is None.	Variant

Properties

Name	Explanation	Data type
meanMultiplier (Read and Write)	The value of the `meanMultiplier` for the transformation function which identifies the multiplier for the mean in the equation.	Double
STDMultiplier (Read and Write)	The value of the `STDMultiplier` for the transformation function which identifies the multiplier for the standard deviation in the function equation.	Double
lowerThreshold (Read and Write)	The value of the `lowerThreshold` for the transformation function which defines the starting value at which to begin applying the specified transformation function.	Double
valueBelowThreshold (Read and Write)	The value that will be assigned to the output cells whose input values are below the `lowerThreshold`.	Variant
upperThreshold (Read and Write)	The value of the `upperThreshold` for the transformation function which defines the ending value at which to stop applying the specified function.	Double
valueAboveThreshold (Read and Write)	The value that will be assigned to the output cells whose input values are above the `upperThreshold`.	Variant

Code sample

Transformation function MSSmall example 1 (Python window)

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

import arcpy
from arcpy.sa import *
from arcpy import env
env.workspace = "c:/sapyexamples/data"
outRescale = RescaleByFunction("elevation", TfMSSmall(1.5, 1.75, "#", "#", "#", "#"), 1, 10)
outRescale.save("c:/sapyexamples/rescaletfms1")

Transformation function MSSmall example 2 (stand-alone script)

Demonstrates how to transform the input data with the RescaleByFunction tool using the TfMSSmall class.