# Diff (Image Analyst)

## Summary

Determines which values from the first input are logically different from the values of the second input on a cell-by-cell basis.

If the values on the two inputs are different, the value on the first input is output. If the values on the two inputs are the same, the output is 0.

## Usage

• Two inputs are necessary for this logical evaluation to take place.

• The order of inputs is relevant for this tool.

• If both inputs are integer, the output will be an integer raster; otherwise, it will be a floating-point raster.

• If both inputs are single band rasters or one of the inputs is a constant, the output will be a single band raster.

• If both inputs are multiband rasters, the tool will perform the operation on each band from one input, and the output will be a multiband raster. The number of bands in each multiband input must be the same.

• If one of the inputs is a multiband raster and the other input is a constant, the tool will perform the operation using the constant value for each band in the multiband input, and the output will be a multiband raster.

• In ArcPy, if both inputs are multidimensional rasters with the same number of variables, the tool will perform the operation for all slices with the same dimension value, and the output will be a multidimensional raster. The variables in the inputs must have the same dimensions or common dimension but no uncommon dimensions.

If both inputs have one variable but different names, set the matchMultidimensionalVariable geoprocessing environment to False to perform the operation.

In ArcPy, if one of the inputs is a multidimensional raster and the other input is a constant, the tool will perform the operation for all slices for all variables using the constant value, and the output will be a multidimensional raster.

## Parameters

 Label Explanation Data Type Input raster or constant value 1 The input to which the second input will be compared.A number can be used as an input for this parameter, provided a raster is specified for the other parameter. To specify a number for both inputs, the cell size and extent must first be set in the environment. Raster Layer; Constant Input raster or constant value 2 The input to which the first input will be compared.A number can be used as an input for this parameter, provided a raster is specified for the other parameter. To specify a number for both inputs, the cell size and extent must first be set in the environment. Raster Layer; Constant

### Return Value

 Label Explanation Data Type Output raster The output raster.The values in the output will be either 0 if the two input values are the same, or the first input value if they are not. Raster

`Diff(in_raster_or_constant1, in_raster_or_constant2)`
 Name Explanation Data Type in_raster_or_constant1 The input to which the second input will be compared.A number can be used as an input for this parameter, provided a raster is specified for the other parameter. To specify a number for both inputs, the cell size and extent must first be set in the environment. Raster Layer; Constant in_raster_or_constant2 The input to which the first input will be compared.A number can be used as an input for this parameter, provided a raster is specified for the other parameter. To specify a number for both inputs, the cell size and extent must first be set in the environment. Raster Layer; Constant

### Return Value

 Name Explanation Data Type out_raster The output raster.The values in the output will be either 0 if the two input values are the same, or the first input value if they are not. Raster

### Code sample

Diff example 1 (Python window)

This example performs a difference operation on two Grid rasters and outputs the result as an IMG raster.

``````import arcpy
from arcpy import env
from arcpy.ia import *
env.workspace = "C:/iapyexamples/data"
outDiff = Diff("degs", "negs")
outDiff.save("C:/iapyexamples/output/outdiff.img")``````
Diff example 2 (stand-alone script)

This example performs a difference operation on two Grid rasters.

``````# Name: Diff_Ex_02.py
# Description: Determines which values from the first input are
#              logically different from the values of the second input
#              on a pixel-by-pixel basis within the Analysis window
# Requirements: Image Analyst Extension

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

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

# Set local variables
inRaster1 = "degs"
inRaster2 = "negs"

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

# Execute Diff
outDiff = Diff(inRaster1, inRaster2)

# Save the output
outDiff.save("C:/iapyexamples/output/outdiff")``````

## Licensing information

• Basic: Requires Image Analyst or Spatial Analyst
• Standard: Requires Image Analyst or Spatial Analyst
• Advanced: Requires Image Analyst or Spatial Analyst