# Diff (Spatial 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.

## Illustration

 OutRas = Diff(InRas1, InRas2)

## 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.

## Syntax

Diff (in_raster_or_constant1, in_raster_or_constant2)
 Parameter 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 be able 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 be able 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.sa import *
env.workspace = "C:/sapyexamples/data"
outDiff = Diff("degs", "negs")
outDiff.save("C:/sapyexamples/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 cell-by-cell basis within the Analysis window
# Requirements: Spatial Analyst Extension
# Author: ESRI

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

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

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

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

# Execute Diff
outDiff = Diff(inRaster1, inRaster2)

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

## Licensing Information

ArcView: Requires Spatial Analyst
ArcEditor: Requires Spatial Analyst
ArcInfo: Requires Spatial Analyst

6/29/2011