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raster calculation in python

Question asked by lpalao on Jun 10, 2014
Latest reply on Jun 22, 2014 by lpinner
Hi ArcGIS Python experts,

I am working on automating my workflow for a project.  For now I am testing my script for only five rasters, then scale-up my analysis if the script will work okay. Once the code is already running, I will incorporate it in another code that I am setting up. I want to get the percentage of each cell using raster calculator. I got the initial code from another thread.

The equation that I am trying to execute is (raster1) / (a specified value) * 100 # computing for percentage

The workflow looks like:
RE_suitable_dek001 / 11.2 * 100
RE_suitable_dek002 / 14.9 * 100
RE_suitable_dek003 / 9.4 * 100
RE_suitable_dek004 / 10.4 * 100
RE_suitable_dek005 / 12.4 * 100

Some details:
Software: ArcGIS 10.2
OS: Windows 7 Prof 64 bit
Python console: PythonWin

import arcpy, os, sys from arcpy import env from arcpy.sa import * arcpy.env.overwriteOutput = True arcpy.CheckOutExtension("Spatial") arcpy.env.workspace = r'E:\Test_awd\awd_pct'  # Raster workspace raster_ws = r'E:\Test_awd\awd_pct'  # Getting the list of raster dataset arcpy.env.workspace = raster_ws rasters = [os.path.join(raster_ws, r) for r in arcpy.ListRasters()]  #Output workspace raster_ow = r'E:\Test_awd\awd_pct'  # Get dictionary (raster1:value, ..., raster5:value) rastVal = {"RE_suitable_dek001":11.2,"RE_suitable_dek002":14.9, "RE_suitable_dek003":9.4, "RE_suitable_dek004":10.4, "RE_suitable_dek005":12.4}  # Raster map algebra for rast in rastVal: # Iterate to all raster in the directory    outRaster = os.path.join(raster_ow, os.path.basename(rast)) # output path and filename of my raster    if rast in rastVal: # iterate my raster if in the dictionary       outRaster = rasters / rastVal[rast] * 100 # the equation that I want to execute...(raster1/11.2)*100       outRaster.save(outRaster + "pct") # output raster with pct (percentage) suffix    else:       print "ERROR: No matching entry in raster value look up dictionary!"



This is the error that I am getting:
Traceback (most recent call last):
  File "C:\Python27\ArcGIS10.2\Lib\site-packages\pythonwin\pywin\framework\scriptutils.py", line 326, in RunScript
    exec codeObject in __main__.__dict__
  File "E:\Python_scripts\ArcGIS\AWD_pct_v2.py", line 25, in <module>
    outRaster = rasters / rastVal[rast] * 100 # the equation that I want to execute...(raster1/11.2)*100
TypeError: unsupported operand type(s) for /: 'list' and 'float'

Thanks,
-Leo

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