Use nested for loop to find all possible combinations of rasters in geodatabase using Python

arcpyfor looppythonraster

I have one geodatabase with multiple rasters where the raster name should automatically identify which category a raster belongs to. I want to combine SLR named rasters with SLOSH named rasters. I am not sure how to approach the nested loop and combine the values of combinations of rasters.

Current code:

import arcpy
from arcpy import env
from pathlib import * 
scriptDir = Path.cwd()
dbDir = scriptDir / 'Inundation_handout.gdb'
env.workspace = str(dbDir)
env.overwriteOutput = True

rasterList = arcpy.ListRasters()
for r1 in rasterList:
    myras = arcpy.Raster(r1)
    for r2 in rasterList:
        if 'SLOSH' in r2 and not 'ft' in r2:

Best Answer

Instead of a nested loop, try itertools.product.

# Completely untested...
from itertools import product
import arcpy
from arcpy import env
from pathlib import * 
scriptDir = Path.cwd()
dbDir = scriptDir / 'Inundation_handout.gdb'
env.workspace = str(dbDir)
env.overwriteOutput = True

sloshList = arcpy.ListRasters("*slosh*")
slrList = arcpy.ListRasters("*slr*")
for r1, r2 in product(sloshList, slrList):
    ras1 = arcpy.Raster(r1)
    ras2 = arcpy.Raster(r2)

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[GIS] Using Nested For Loop in ArcPy

First of all if I were you, I would add two counters, one for each loop. After the script finishes you should simply print them out. Also note that the counter

Secondly the outer for loop runs your inner loop that compares your data. That way your count is increased for each match the inner loop finds. If you really want to see the real count value, you should put the line of code where you increment the count variable outside the if clause.

import arcpy
gebaudepoints_no = 68
hausnummer_no = 62
count = 0

with arcpy.da.UpdateCursor('hausnummer_cropped5', ['HAUSNR','STRASSE','SHAPE@XY']) as cursor1:

for row1 in cursor1:
  count1 += 1
  with arcpy.da.UpdateCursor('gebaudepoints_cropped5 - Kopie2', ['ZA3',     'ZA2','GN5','SHAPE@XY']) as cursor2: 
     count2=0
     for row2 in cursor2:    
            count2 +=1 #this one will increase waaaay too 
                       #much so just set it to zero before the loop and you're good
                       #but also note that it will show the length of 
                       #the last item in cursor1 within the cursor2
            if (row2[0] == row1[0]) and (row2[1] == row1[1]): # and (row2[2] > 0):
              #woo! the if condition is met lets print why here
              X = row1[2][0] 
              Y = row1[2][1]  
              count += 1 

              cursor2.updateRow([row2[0], row2[1], row2[2], [(X),(Y)]])
              #cursor2.deleteRow()

print("Counter for outer loop: "+str(count1)+" and the inner one "+str(count2))

What I would add to your code is, some sort of result printing, so you can display data when your if condition is met. Then you can see what points are missing and print that data out to see why they dont match and change the if clause correctly. So to direct you into where to look on what to print, I would the check values of your row2 list maybe you can find a label to print in there.

Best Answer

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[GIS] Using Nested For Loop in ArcPy

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