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Thanks, @curtvprice for your help. Yes, it is a raster dataset name "combo" and those are the field names from the raster table. I trying to calculate a field called "Bark_load" based on the following equation. VB 7.437 /(1+937.8 * Exp ( -1.905 *( Bark_r *(1 - Exp ( - Bark_k * since_fire ) )+ Bark_c ))) Python 7.437 /(1+937.8 * math.exp(-1.905 *( !Bark_r! *(1 - math.exp(- !Bark_k! * !Since_Fire! )) + !Bark_c! ))) please note: exp is exponential function not Exp (Spatial Analyst) I have a modelbuilder and this equation works there as VB and Python. Thanks for any further help.
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03-17-2021
03:01 PM
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Hello colleagues I am trying to use a formula in python. It is a raster dataset and I am trying to calculate a field based on an equation. Here is the code ==================== inTable = "C:/Data/A3_Large_projects/Fuelloadmodels/Data/GDB/Yr2021.gdb/combo" fieldName = "Bark_load" expression = "t_RF(!Bark_r!, !Bark_k!, !Bark_c!, !since_fire!)" codeblock = """ def t_RF(Bark_r, Bark_k, Bark_c, since_fire): if since_fire >= 0: return 7.437 /(1+937.8 * Exp ( -1.905 *( Bark_r *(1 - Exp ( - Bark_k * since_fire ) )+ Bark_c ))) else: return 999 """ arcpy.CalculateField_management(inTable, fieldName, expression, "PYTHON_9.3", codeblock) ==================== End code Error message starts ==================== Traceback (most recent call last): File "C:\Data\A3_Large_projects\Fuelloadmodels\Python_script\Fuelhazard.py", line 126, in <module> arcpy.CalculateField_management(inTable, fieldName, expression, "PYTHON_9.3", codeblock) File "C:\Program Files (x86)\ArcGIS\Desktop10.5\ArcPy\arcpy\management.py", line 3661, in CalculateField raise e ExecuteError: ERROR 000539: Error running expression: t_RF(2.5, 0.2, 0.7, 1) Traceback (most recent call last): File "<expression>", line 1, in <module> File "<string>", line 4, in t_RF NameError: global name 'Exp' is not defined Failed to execute (CalculateField). ==================== End error message I am relatively new in python. Trying to understand the error message. Will appreciate any help. Thanks
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03-16-2021
07:28 PM
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Hi Where is the download link for latest Patch Analyst, manual and tutorial? Thanks for help
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12-07-2017
03:27 PM
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Hi Does anyone know how to calculate sum of area within a polygon? I have two shapefiels of addres cluster and cencus unit. want to do an areal interpolation, so I want to get sum of area of clusters witin census unit. Thanks 🙂 Sal
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05-13-2012
09:41 PM
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