Calling variable filename within Con function in ArcPY?

Question

I want to replace the even pixel values of a raster from 1 and rest with 0. Since, I have 100+ raster files therefore, I am calling filenames in loop.

I copied the python snippet after applying con operation on a single file that worked fine. However, it fails in the script and shows error as,

NameError: name 'fin' is not defined Failed to execute (RasterCalculator).

Here, fin is the variable name.

import arcpy

Path = "Path/to/folder/"

for year in range(2010,2016):
    for day in range(1,369,8):

        fin = Path + 'Raster'+ str(year) + "_D" + str(day).zfill(3) + ".tif"    
        out = Path + 'Processed_Raster'+ str(year) + "_D" + str(day).zfill(3) + ".tif"
        arcpy.gp.RasterCalculator_sa("""Con(Mod(fin,2) == 0,1,0)""", out)

How to resolve this error?

Answer 1

I think your problem might be the expression is a string to when the raster calc runs it can't find the "fin" variable. I rewrote the expression to use the arcpy.sa module for the Con and Mod functions. I would also build a list of tif files in a directory (assuming all your tifs are contained in it and not more) so that you don't miss any and don't try to use a raster that may not exist in the directory.

try this:

import arcpy, os

Path = r"Path\to\folder"

finFiles = [file for file in os.listdir(Path) if file.endswith('.tif')]

for file in finFiles:
    fin = os.path.join(Path,file)
    out = os.path.join(Path,(file.replace('Raster','Processed_Raster')))
    arcpy.gp.RasterCalculator_sa("Con(Mod('{0}',2) == 0,1,0)".format(fin), out)

Answer 2

Raster calculator is executing your string as its own code, and the variable fin does not exist in that code. Rather than passing in the variable, pass in the actual string the code needs. I believe changing your last line to this would work:

arcpy.gp.RasterCalculator_sa("""Con(Mod(%s,2) == 0,1,0)""" % fin, out)