Determine percentage of a specified cell value within a defined neighborhood

Summary

Steps for finding the percentage of a particular cell value within a defined focal neighborhood.

Procedure

1. Create an intermediate grid with values of 1 where the input grid meets your desired condition, and 0 or NODATA everywhere else.
   
   
2. Use the FOCALSUM function, with the DATA option on the intermediate grid, to determine the number of cells in the focal neighborhood that have a value of 1.
   
   
3. Divide the sum by the number of cells in the focal neighborhood for the percentage.
   
   

   Code:
   PERCENTAGE_GRID = FOCALSUM( con( <input_grid> == <value>, 1 ), RECTANGLE, 3, 3, DATA) / 9  

   
   
   

   Note:
   The above example nests the three steps into one expression, which determines the percentage of <value> within a 3 by 3 focal area containing 9 cells.