topic Re: calculate mean of selected raster chosen from multiple raster using ArcPy in Python Questions

calculate mean of selected raster chosen from multiple raster using ArcPy

ShouvikJha — Sat, 11 Dec 2021 19:42:41 GMT

I am trying to calculate mean of selected raster chosen from multiple raster. I have multiple raster file in different month folder, i am trying to select only two raster (e.g For JANUARY : 001_Max_Temper.tif, 001_Min_Temper.tif) from different month folder (JANUARY, FEBRUARY....DECEMBER) and calculate the mean of those selected raster and save it as on same month folder (e.g output name, JANUARY: 001_Mean_Temp).

I have written a code to do this task but i am getting error massage while i am running this code. Below i have attached my code.

import arcpy, os, calendar
from arcpy import env
from arcpy.sa import *
arcpy.CheckOutExtension("Spatial")
arcpy.env.parallelProcessingFactor = "100%"
topWorkspace = r'D:\SWAT-WEATHER-DATA2'
arcpy.env.workspace = topWorkspace

# Get dict of months and month-number (i.e. January = 001, March = 003 etc.)
months = {calendar.month_name[i].upper(): str(i).zfill(3) for i in range(1, 13)} # Get dict of months and month number (i.e. January = 001, March = 003 etc.)

# Step through list of all folders
for folderPath in arcpy.ListWorkspaces():
    baseName = os.path.basename(folderPath).upper()
    if baseName in months: # Test that subfolder is a month name
        monthNumber = months[baseName] # Get month-number for use in output filename
        arcpy.env.workspace = folderPath
        rasterList = arcpy.ListRasters('*Max_Temper.tif', '*Min_Temper.tif')
        # Execute CellStatistics
        outCellStatistics = CellStatistics(rasterList, "MEAN", "NODATA")
        #Save the output
        outRasterName = outCellStatistics, "Mean_Temp_{}.tif".format(monthNumber)
        outCellStatistics.save(outRasterName)
        

#print done
print 'done'‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

Re: calculate mean of selected raster chosen from multiple raster using ArcPy

DarrenWiens2 — Wed, 24 Aug 2016 18:20:04 GMT

What/where is the error?

Re: calculate mean of selected raster chosen from multiple raster using ArcPy

ShouvikJha — Sat, 11 Dec 2021 19:42:44 GMT

the following error massage i am getting

Message File Name Line Position 
Traceback 
 <module> <module1> 20 
 CellStatistics C:\Program Files\ArcGIS\Desktop10.1\arcpy\arcpy\sa\Functions.py 2817 
 swapper C:\Program Files\ArcGIS\Desktop10.1\arcpy\arcpy\sa\Utils.py 47 
 wrapper C:\Program Files\ArcGIS\Desktop10.1\arcpy\arcpy\sa\Functions.py 2813 
RuntimeError: ERROR 999998: Unexpected Error. ‍‍‍‍‍‍‍

Re: calculate mean of selected raster chosen from multiple raster using ArcPy

XanderBakker — Wed, 24 Aug 2016 18:53:48 GMT

There are a number of errors in the code. The generation of the "months" dictionary is well defined, but keep in mind that the folder names should be in the language of what is defined in the regional settings. In my case it returns in Spanish:

{'JULIO': '007', 'SEPTIEMBRE': '009', 'MARZO': '003', 'JUNIO': '006', 'ABRIL': '004', 'ENERO': '001', 'AGOSTO': '008', 'FEBRERO': '002', 'DICIEMBRE': '012', 'NOVIEMBRE': '011', 'MAYO': '005', 'OCTUBRE': '010'}

The line:

rasterList = arcpy.ListRasters('*Max_Temper.tif', '*Min_Temper.tif')‍

Will not work, since "arcpy.ListRasters" allows two parameters; the first is the wildcard, the second is the raster type. You are specifying two wildcards. You can either use:

rasterList = arcpy.ListRasters('*_Temper.tif')‍

... or create two lists and combine them.

The other line where the code will produce an error is:

outRasterName = outCellStatistics, "Mean_Temp_{}.tif".format(monthNumber)‍

outCellStatistics is a raster object. You will have to use something like (ws_out is your output workspace, and needs to be defined before):

outRasterName = os,.path.join(ws_out, "Mean_Temp_{}.tif".format(monthNumber))‍

Re: calculate mean of selected raster chosen from multiple raster using ArcPy

ShouvikJha — Sat, 11 Dec 2021 19:42:47 GMT

Xander Bakker‌ . i have corrected the code, but still error. month folder name in my database is (JANUARY, FEBRUARY ....DECEMBER)

import arcpy, os, calendar
from arcpy import env
from arcpy.sa import *
arcpy.CheckOutExtension("Spatial")
arcpy.env.parallelProcessingFactor = "100%"
topWorkspace = r'D:\SWAT-WEATHER-DATA2'
arcpy.env.workspace = topWorkspace
# Get dict of months and month-number (i.e. January = 001, March = 003 etc.)
months = {calendar.month_name[i].upper(): str(i).zfill(3) for i in range(1, 13)} # Get dict of months and month number (i.e. January = 001, March = 003 etc.)
# Step through list of all folders
for folderPath in arcpy.ListWorkspaces():
 baseName = os.path.basename(folderPath).upper()
 if baseName in months: # Test that subfolder is a month name
 monthNumber = months[baseName] # Get month-number for use in output filename
 arcpy.env.workspace = folderPath
 rasterList1 = arcpy.ListRasters('*Max_Temper.tif')
 rasterList2 = arcpy.ListRasters('*Min_Temper.tif')
#Calculate maen
 ws_out = (rasterList1 + rasterList2) / 2
outRasterName = os, path.join(ws_out, "Mean_Temp_{}.tif".format(monthNumber))
#print done
print 'done'‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

Re: calculate mean of selected raster chosen from multiple raster using ArcPy

XanderBakker — Wed, 24 Aug 2016 19:17:06 GMT

You are trying to "divide" the two lists by two (line 19). The lists are no raster objects. You should use the combined list as input for the CellStatistics tool.

the ws_out should be the name of the folder (workspace) where you want to store the resulting rasters.

Furthermore, on line 20 you have "os, path" it should be "os.path"

Re: calculate mean of selected raster chosen from multiple raster using ArcPy

XanderBakker — Sat, 11 Dec 2021 19:42:49 GMT

... or to be more specific, something like this:

import arcpy, os, calendar
from arcpy.sa import *
arcpy.CheckOutExtension("Spatial")
arcpy.env.parallelProcessingFactor = "100%"
topWorkspace = r'D:\SWAT-WEATHER-DATA2'
ws_out = r'D:\SWAT-WEATHER-DATA2\MeanRasters' ### create this folder!!!
arcpy.env.workspace = topWorkspace

# Get dict of months and month-number (i.e. January = 001, March = 003 etc.)
months = {calendar.month_name[i].upper(): str(i).zfill(3) for i in range(1, 13)} # Get dict of months and month number (i.e. January = 001, March = 003 etc.)


# Step through list of all folders
for folderPath in arcpy.ListWorkspaces():
    baseName = os.path.basename(folderPath).upper()
    if baseName in months: # Test that subfolder is a month name
        monthNumber = months[baseName] # Get month-number for use in output filename
        arcpy.env.workspace = folderPath

        # list rasters
        rasterList1 = arcpy.ListRasters('*Max_Temper.tif')
        rasterList2 = arcpy.ListRasters('*Min_Temper.tif')

        # combine lists
        rasterList = rasterList1 + rasterList2

        # Execute CellStatistics
        outCellStatistics = CellStatistics(rasterList, "MEAN", "NODATA")

        #Save the output
        outRasterName = os.path.join(ws_out, "Mean_Temp_{}.tif".format(monthNumber))
        outCellStatistics.save(outRasterName)

#print done
print 'done'‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

Re: calculate mean of selected raster chosen from multiple raster using ArcPy

XanderBakker — Wed, 24 Aug 2016 19:36:52 GMT

... and maybe you should include a statement to check the length of the rasterList before you execute the CellStatistics tool. If you come across an empty folder you don't want to try to continue with the CellStatistics.

Re: calculate mean of selected raster chosen from multiple raster using ArcPy

ShouvikJha — Wed, 24 Aug 2016 19:39:59 GMT

xander_bakker‌ Thank you. code is working fine. Once again thank you for your kind cooperation.

Re: calculate mean of selected raster chosen from multiple raster using ArcPy

ShouvikJha — Wed, 24 Aug 2016 19:47:36 GMT

Xander Bakker‌ . yes i have executed this function before performing cell-statistics to get the list of raster as per your suggestion . Thank you

print rasterList‍‍

Re: calculate mean of selected raster chosen from multiple raster using ArcPy

DanPatterson_Retired — Wed, 24 Aug 2016 20:00:00 GMT

perhaps you could mark Xander's response correct so there is some closure to this thread

Re: calculate mean of selected raster chosen from multiple raster using ArcPy

ShouvikJha — Wed, 24 Aug 2016 20:02:24 GMT

Dan_Patterson‌ . I already marked it correct. Thank you

Re: calculate mean of selected raster chosen from multiple raster using ArcPy

XanderBakker — Sat, 11 Dec 2021 19:42:52 GMT

Actually I was referring at doing something like this (see line 4):

        # combine lists
        rasterList = rasterList1 + rasterList2

        if len(rasterList) > 1:
            # Execute CellStatistics
            outCellStatistics = CellStatistics(rasterList, "MEAN", "NODATA")

            #Save the output
            outRasterName = os.path.join(ws_out, "Mean_Temp_{}.tif".format(monthNumber))
            outCellStatistics.save(outRasterName)
‍‍‍‍‍‍‍‍‍‍

I use "> 1", not sure what happens if the list would contain a single raster...

Anyway, I'm glad it works!

Re: calculate mean of selected raster chosen from multiple raster using ArcPy

ShouvikJha — Wed, 24 Aug 2016 20:27:42 GMT

Xander Bakker‌. This one is very useful step to verify the length of rasterList before calculating mean. Thank you

Re: calculate mean of selected raster chosen from multiple raster using ArcPy

ShouvikJha — Sat, 11 Dec 2021 19:42:55 GMT

Xander Bakker‌. I just tried to modify above code for another calculation, But error occurring. Please cooperate me. Below i shown the modified code along with error massage,

Message File Name Line Position
Traceback
 <module> D:\Arc-GIS-Python-Script\T_SCALAR.py 27
 Minus C:\Program Files\ArcGIS\Desktop10.1\arcpy\arcpy\sa\Functions.py 3840
 swapper C:\Program Files\ArcGIS\Desktop10.1\arcpy\arcpy\sa\Utils.py 47
 wrapper C:\Program Files\ArcGIS\Desktop10.1\arcpy\arcpy\sa\Functions.py 3837
TypeError: expected a raster or layer name‍‍‍‍‍‍‍‍‍‍‍‍‍‍

import arcpy, os, calendar
from arcpy.sa import *
from arcpy import env
arcpy.env.overwriteOutput = True
arcpy.CheckOutExtension("Spatial")
arcpy.env.parallelProcessingFactor = "100%"
topWorkspace = r'D:\SWAT-WEATHER-DATA2'
ws_out = r'D:\SWAT-WEATHER-DATA2\TScalar' ### Output folder!!!
arcpy.env.workspace = topWorkspace
# Get dict of months and month-number (i.e. January = 001, March = 003 etc.)
months = {calendar.month_name[i].upper(): str(i).zfill(3) for i in range(1, 13)} # Get dict of months and month number (i.e. January = 001, March = 003 etc.)

# Step through list of all folders
for folderPath in arcpy.ListWorkspaces():
 baseName = os.path.basename(folderPath).upper()
 if baseName in months: # Test that subfolder is a month name
 monthNumber = months[baseName] # Get month-number for use in output filename
 arcpy.env.workspace = folderPath
# Raster1 take Mean_Temp raster from all month folder(e.g for january: Mean_temp_001.tif) and Raster 2 is constant month of october raster
 rasterList1 = arcpy.ListRasters(r'Mean_Temp*.tif')
 rasterList2 = arcpy.Raster(r'D:\SWAT-WEATHER-DATA2\OCTOBER\Mean_Temp_010.tif')

 ### combine list raster into equation

 #TScalar1 = 1.1814 / (1 + EXP(0.2 * (rasterList2 - 10- rasterList1)))
 TScalar1 = 1.1814 / ((1 + Exp(0.2 * (rasterList2 - 10 - rasterList1))))
 
 #TScalar2 = 1/(1+EXP(0.3*(- rasterList2 - 10 + rasterList1)))
 TScalar2 = 1 / (1 + Exp(0.3 * (- rasterList2 - 10 - rasterList1)))

# Multiply TScalar1 and TScalar2
 TScalar = (TScalar1 * TScalar2)

#Save the output
 outRasterName = os.path.join(ws_out, "T_SCALAR_{}.tif".format(monthNumber))
 TScalar.save(outRasterName)
 print outRasterName

#print done
print 'done'‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

Re: calculate mean of selected raster chosen from multiple raster using ArcPy

XanderBakker — Thu, 25 Aug 2016 12:46:50 GMT

On line 26 and 29 you are trying to do a calculation on a list. This is not possible. You should perform the calculation using Raster objects.

What exactly are you trying to do? Can you add a brief explanation?

Re: calculate mean of selected raster chosen from multiple raster using ArcPy

ShouvikJha — Thu, 25 Aug 2016 12:55:27 GMT

I want to calculate two different peramater using Monthly mean Temp. data using that equation. That Monthly mean Temp data stored in all monthly folder based on different month, for raster1 i want to take mean temp. raster from different month (e.g. JANAURAY : Mean_Temp_001, FEBRUARY: Mean_Temp_002 so on) and raster2 i want to keep constant the raster map of Month of October data (Mean_Temp_010).

Later stage, i want to multiply TScalar1 and TScalar2 and save it TScalar folder

Re: calculate mean of selected raster chosen from multiple raster using ArcPy

XanderBakker — Sat, 11 Dec 2021 19:42:57 GMT

If I understand it correctly, you would need to do something like this:

import arcpy, os, calendar
from arcpy.sa import *
from arcpy import env
arcpy.env.overwriteOutput = True
arcpy.CheckOutExtension("Spatial")
arcpy.env.parallelProcessingFactor = "100%"
topWorkspace = r'D:\SWAT-WEATHER-DATA2'
ws_out = r'D:\SWAT-WEATHER-DATA2\TScalar' ### Output folder!!!
arcpy.env.workspace = topWorkspace

# Get dict of months and month-number (i.e. January = 001, March = 003 etc.)
months = {calendar.month_name[i].upper(): str(i).zfill(3) for i in range(1, 13)} 

# Step through list of all folders
for folderPath in arcpy.ListWorkspaces():
    baseName = os.path.basename(folderPath).upper()
    if baseName in months: # Test that subfolder is a month name
        monthNumber = months[baseName] # Get month-number for use in output filename
        arcpy.env.workspace = folderPath

        # Raster1 take Mean_Temp raster from all month folder(e.g for january: Mean_temp_001.tif) and Raster 2 is constant month of october raster
        rasterList1 = arcpy.ListRasters(r'Mean_Temp*.tif')
        ras_oct = arcpy.Raster(r'D:\SWAT-WEATHER-DATA2\OCTOBER\Mean_Temp_010.tif')

        for ras_name in rasterList1:
            ras_mean = arcpy.Raster(os.path.join(folderPath, ras_name))

            # TScalar1 = 1.1814 / (1 + EXP(0.2 * (rasterList2 - 10 - rasterList1)))
            ras_scal1 = 1.1814 / ((1 + Exp(0.2 * (ras_oct - 10 - ras_mean))))

            # TScalar2 = 1/(1+EXP(0.3*(- rasterList2 - 10 + rasterList1)))
            ras_scal2 = 1 / (1 + Exp(0.3 * (-1 * ras_oct - 10 - ras_mean)))

            # Multiply TScalar1 and TScalar2
            ras_scal = (ras_scal1 * ras_scal2)

            # Save the output
            outRasterName = os.path.join(ws_out, "T_SCALAR_{}.tif".format(monthNumber))
            print outRasterName
            ras_scal.save(outRasterName)
            

#print done
print 'done'‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

For every month it will do the calculations. However, not sure if this will be correct for the month of October, when the mean raster is the same as the constant raster.

Re: calculate mean of selected raster chosen from multiple raster using ArcPy

ShouvikJha — Thu, 25 Aug 2016 13:23:15 GMT

xander_bakker‌. Thank you very much for your kind support. Code working perfectly.

Re: calculate mean of selected raster chosen from multiple raster using ArcPy

XanderBakker — Thu, 25 Aug 2016 13:51:48 GMT

Glad to hear that. What about the month October? Does the result make sense?