Conditional Reclassification using Raster Calculator

Question

There are several questions about conditional reclassification on the Stack Exchange, but I haven't been able to find exactly what I need...

In my workspace, I have a list of raster layers (8 bit unsigned integer) that have values from 0-255. I am attempting to use conditional statements within the raster calculator to create a binary (0 and 1) layer in which only values between 90-100 are reclassified to 1 and the remaining values are reclassified to 0.

The code snippet I am working with can be seen below

# IMPORT MODULES
import arcpy, os

# SET GEO_PROCESSING ENVIRONMENTS
arcpy.env.workspace = r"C:\Users\BP_Mosaics"
outws = r"C:\Users\90BP_Mosaics"

# CREATE A LIST OF THE MOSAIC RASTER LAYERS
rasterList = arcpy.ListRasters("*", "tif")

# CREATE LOOP TO RECLASSIFY ALL BP MOSAICS INTO 0s and 1s
# CREATE LOOP TO RECLASSIFY ALL BP MOSAICS INTO 0s and 1s
for i in rasterList:
    inputRaster = (os.path.join(env.workspace, i))
    filename = i[-18:-4] + '_01.tif'
    outname = os.path.join(outws, filename)
    arcpy.gp.RasterCalculator_sa("Con(((" + inputRaster + ">= 90) & (" + inputRaster + "<= 100)), 1, 0)", outname)

I am not seeing any immediate errors in the code, however something does not seem to be working properly as I receive the following error message...

arcgisscripting.ExecuteError: ERROR 000539: (null)
Failed to execute (RasterCalculator).

Would anyone happen to know what is happening here?

Answer 1

I think there are 2 problems: i coming from your rasterList is not being constructed correctly and how you are building your expression to use in CON().

Firstly you create rasterList by searching a workspace and this returns a list of raster names, not the full path to the raster. So your input into your CON() expression should be something like:

inputRaster = os.path.join(outws, i)
arcpy.gp.RasterCalculator_sa("Con(((" + inputRaster +" >= 90) & (" + inputRaster +" <= 100)), 1, 0)", outname)

UPDATE:

I realised that you don't really need to call the CON tool within a Raster calculator, you are boxing a tool within a tool. So you just need to call the CON tool which has much easier syntax to understand. I also show you best practise which you were not doing, checking in/out extensions and encapsulating your code within a try/except to capture errors.

Having reviewed your updated code I have made the following edits so that it works, just change the paths to your requirements:

# IMPORT MODULES
import arcpy, os
arcpy.CheckOutExtension('Spatial')
try:

    # SET GEO_PROCESSING ENVIRONMENTS
    arcpy.env.workspace = r"D:\GIS\GIS Data"
    outws = r"D:\GIS"

    # CREATE A LIST OF THE MOSAIC RASTER LAYERS
    rasterList = arcpy.ListRasters("*", "tif")

    # CREATE LOOP TO RECLASSIFY ALL BP MOSAICS INTO 0s and 1s
    for i in rasterList:
        inputRaster = (os.path.join(arcpy.env.workspace, i))
        filename = i[-18:-4] + '_01.tif'
        outname = os.path.join(outws, filename)
        arcpy.gp.Con_sa(inputRaster, "1", outname, "0", '"Value" >=90 AND "Value" <=100')
except arcpy.ExecuteError:
    # Geoprocessor threw an error
    print(arcpy.GetMessages(2))
finally:
    arcpy.CheckInExtension('Spatial')