Focal Statistics (Spatial Analyst)
Summary
Calculates for each input cell location a statistic of the values within a specified neighborhood around it.
Illustration
Usage

If the input raster is of floating point type, only the Mean, Maximum, Minimum, Range, STD, and Sum statistics are available; the Majority, Minority, Median and Variety statistics are not permitted. If the input raster is of integer type, all the statistics types are available.

The values on the output raster depend on the operation.

When a circular, annulusshaped, or wedgeshaped neighborhood is specified, some of the outer diagonal cells may not be considered in the calculations since the center of the cell must be encompassed within the neighborhood.

The Irregular and Weight Neighborhood types require a Kernel file be specified. Kernel files should have a ".txt" file extension.
See the Irregular and Weight sections of How Focal Statistics works for information on creating and using kernel files.

Only for the statistics types of Mean, Standard Deviation, or Sum can the Neighborhood type can be set to Weight.

Input NoData cells may receive a value in the output if the Ignore NoData in calculations option is checked, provided at least one cell within the neighborhood has a valid value.
Syntax
Parameter  Explanation  Data Type 
in_raster 
The raster to perform the focal statistics calculations on.  Raster Layer 
neighborhood (Optional) 
The Neighborhood class dictates the shape of the area around each cell used to calculate the statistic. The different types of neighborhood available are: NbrAnnulus, NbrCircle, NbrRectangle, NbrWedge, NbrIrregular, and NbrWeight. The following are the forms of the neighborhoods:
The {CELL  MAP} parameter defines the distance units as either being Cell units or Map units. The default neighborhood is a square NbrRectangle with a width and height of 3 cells.  Neighborhood 
statistics_type (Optional) 
The statistic type to be calculated.
The default statistic type is MEAN.  String 
ignore_nodata (Optional) 
Denotes whether NoData values are ignored by the statistic calculation.
 Boolean 
Return Value
Name  Explanation  Data Type 
out_raster 
The output focal statistics raster.  Raster 
Code Sample
This example calculates the leastfrequently occuring value in a ringshaped neighborhood around each cell in the input raster.
import arcpy from arcpy import env from arcpy.sa import * env.workspace = "C:/sapyexamples/data" outFocalStat = FocalStatistics("elevation", NbrAnnulus(5, 10, "CELL"), "MINORITY", "NODATA") outFocalStat.save("C:/sapyexamples/output/focalstat01")
This example determines the least frequently occurring value in a 10by10 neighborhood around each cell in the input raster.
# Name: FocalStatistics_Ex_02.py # Description: Calculates a statistic on a raster over a specified # neighborhood. # 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 inRaster = "elevation" neighborhood = NbrRectangle(10, 10, "CELL") # Check out the ArcGIS Spatial Analyst extension license arcpy.CheckOutExtension("Spatial") # Execute FocalStatistics outFocalStatistics = FocalStatistics(inRaster, neighborhood, "MINORITY", "") # Save the output outFocalStatistics.save("C:/sapyexamples/output/focalstatout")