Perform Raster Calculation from Multiple Sub-folder Using ArcPy

[ShouvikJha]

I have five subfolders with Rasters name with the same parameter. I am trying to figure out a way to Loop average of all  raster and save output raster in outfolder . For instance 

Subfolder1   Subfolder2   Subfolder3   Subfolder4    Subfolder5   Outfolder
r001_NPP.tif r001_npp.tif r001_NPP.tif r_001_NPP.tif r001_NPP.tif r001_MEAN_NPP.tif‍‍‍‍‍‍

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I have tried to write code for this, Below i post my code what i have so far

import arcpy, os, glob
arcpy.CheckOutExtension("Spatial")

ws1 = glob.glob(r'D:\subfolder1\*.tif')
ws2 = glob.glob(r'D:\subfolder2\*.tif')
ws3 = glob.glob(r'D:\subfolder3\*.tif')
ws4 = glob.glob(r'D:\subfolder4\*.tif')
ws5 = glob.glob(r'D:\subfolder5\*.tif')
outws = r'D:\outfolder'

for r in ws1, ws2, ws3, ws4:
    basename = os.path.basename(r).split("_")[0]
    r1 = arcpy.sa.Raster(os.path.join(ws1, basename + "r_NPP.tif"))
    r2 = arcpy.sa.Raster(os.path.join(ws2, basename + "r_NPP.tif"))
    r3 = arcpy.sa.Raster(os.path.join(ws3, basename + "r_NPP.tif"))
    r4 = arcpy.sa.Raster(os.path.join(ws4, basename + "r_NPP.tif"))
    r5 = arcpy.sa.Raster(os.path.join(ws5, basename + "r_NPP.tif"))
    

    result = (r1 + r2 + r3 + r4 + r5) / 5
    outname = basename + "r_Mean_NPP.tif"

    result.save(os.path.join(outws, outname))‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

[curtvprice]

I would look into arcpy.da.walk() to generate the list of rasters, and use the Spatial Analyst Cell Statistics tool on the raster list.

Walk—Help | ArcGIS for Desktop 

Cell Statistics—Help | ArcGIS for Desktop 

Cell Statistics is much more efficient, especially with long lists of rasters -- and it also has a very handy DATA/NODATA option so null is treated as zero in the cell by cell summation.

Untested code:

import arcpy
arcpy.CheckOutExtension("spatial")
from arcpy.sa import *

# generate list of rasters
workspace = r"D:\"
rasters = []
walk = arcpy.da.Walk(workspace, datatype="RasterDataset", type="TIF")
for dirpath, dirnames, filenames in walk:
    for filename in filenames:
    rasters.append(os.path.join(dirpath, filename))

# calculate mean
sum = CellStatistics(rasters, "MEAN")
sum.save(os.path.join(out_workspace, "npp_sum.tif")‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

[ShouvikJha]

Thank you. I have updated my suggested by you, problem still persist, i am not understanding how to iterate through each folder, take all series of 001_NPP from all folder and calculate average oh them and save it as 001_NPP_MEAN, below is my updated code and along with code i have attached reference raster also which i am using for my raster calculation, 

import arcpy
arcpy.CheckOutExtension("spatial")
from arcpy.sa import *

# generate list of rasters
workspace = r"D:\TEST"
out_workplace = "D:\TEST\MEAN_NPP"

rasters = []
walk = arcpy.da.Walk(workspace, datatype="RasterDataset", type="TIF")
for dirpath, dirnames, filenames in walk:
    for filename in filenames:
    rasters.append(os.path.join(dirpath, filename))

# calculate mean
sum = CellStatistics(rasters, "MEAN")
sum.save(os.path.join(out_workspace, "npp_sum.tif")‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

[DanPatterson_Retired]

your code is only minimally updated from what Neil provided and it was untested.  

What was the error message?

issues to get you started...

• Line 13 is not indented properly
• Walk—Help | ArcGIS for Desktop you need to check the correct format
• datatype and type in Walk are incorrect
• you shouldn't use from X import *

You need to provide some input to the solution and to do that providing commentary as to what went wrong and where would go a long way

[ShouvikJha]

Dan . thanks , you are right. I didn't post the error massage. Line no 13 i am getting the Indentation Error massage. I tried to fix it but not solved yet. error massage below 

File "<module1>", line 13
    rasters.append(os.path.join(dirpath, filename))
          ^
IndentationError: expected an indented block
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[DanPatterson_Retired]

Ok.... add four (4) more spaces to the beginning of line 13 so it is indented properly

Here is the python style guide recommendations PEP 8 -- Style Guide for Python Code | Python.org 

[ShouvikJha]

Dan , thanks . I have solved the indentation error, and i updated my code but still i could not solve the problem, updated code below 

error masage

ile "<module1>", line 18
    sum.save(os.path.join(out_workspace, 'r{0}_MEAN_NPP.TIF'.format(ras_num)
                                                                           ^
SyntaxError: invalid syntax‍‍‍‍

Updated Code 

import arcpy
arcpy.CheckOutExtension("spatial")
from arcpy.sa import *

# generate list of rasters
workspace = r"D:\TEST"
out_workplace = "D:\TEST\MEAN_NPP"

for ras_num in [str(i).zfill(3) for i in range(1, 12)]:
 rasters = []
walk = arcpy.da.Walk(workspace, datatype="RasterDataset", type="TIF")
for dirpath, dirnames, filenames in walk:
    for filename in filenames:
     rasters.append(os.path.join(dirpath, filename))

# calculate mean
sum = CellStatistics(rasters, "MEAN")
sum.save(os.path.join(out_workspace, 'r{0}_MEAN_NPP.TIF'.format(ras_num)‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

[RebeccaStrauch__GISP]

Change line 7 to

out_workplace = r"D:\TEST\MEAN_NPP"

You missed the "r" in that path.

[XanderBakker]

In addition, line 18 is missing 2 closing brackets "))" at the end of the line. Perhaps you didn't copy the entire line.

[curtvprice]

Hey no fair. 😉