How to make a loop work?

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08-20-2019 01:35 PM
JessicaRamirez1
New Contributor II

Hi, 

I have a survey made from survey 123, I have a point layer representing assets. The goal is to complete the survey for every asset. I have a field in my points layer called CompleteY_N, by default the attribute is 'Not Completed'. I want the attribute to change to 'complete' as a survey it summited and loop through until all assets say complete in the CompleteY_N field. 

I wrote a script that selects by location and then uses UpdateCursor to change the attribute to complete. I have also used field calculate to change the selected features to complete ( not sure which way is better). 

I am not sure how to do a loop like this, or if I have even explained what I am trying to do correctly.  

Here is my script. 

import arcpy

# Input property
inPropertypntfc = r"G:\GIS\ESRI\Staging\Survey123\Testing\New File Geodatabase.gdb\propertypnts"
print(inPropertypntfc)

# input survey feature class
inSurveyfc = r"G:\GIS\ESRI\Staging\Survey123\Testing\New File Geodatabase.gdb\retailpt2"
print(inSurveyfc)

# Make feature layer of feature classes to allow selection
arcpy.MakeFeatureLayer_management(inPropertypntfc, "Propertypntlyr")
arcpy.MakeFeatureLayer_management(inSurveyfc, "Surveylyr")


# select intersecting points
arcpy.SelectLayerByLocation_management("Propertypntlyr", "INTERSECT", "Surveylyr")
print ("select")

# Update Cursor for point layer
cursor = arcpy.da.UpdateCursor("Propertypntlyr", ["CompleteY_N"])
print (cursor)
for row in cursor:
    cursor.updateRow(["Completed"])
print ("Done")

del row
del cursor
Tags (2)
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5 Replies
DuncanHornby
MVP Frequent Contributor

Have you tried searching the internet on how to loop in python, here is one such website?

JessicaRamirez1
New Contributor II

Thank you for the info

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JoeBorgione
MVP Esteemed Contributor

As Duncan Hornby‌ suggests, for loops are a standard operation in python.  I've always said, give me a list to Ioop through and I can change the world...

However, I'm unclear what it is you need to loop through?  In your current for loop through the cursor object, what is the purpose of passing a list as the value?  (Line 2  below)

for row in cursor:
    cursor.updateRow(["Completed"])
That should just about do it....
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LukeWebb
Occasional Contributor III

I wrote this script based on my understanding of your explanation (Which was a little hazy!)

I kept your existing code exactly as it was just moved it into a function, then added one new function, and a Loop.

Hopefully this helps    


import arcpy
import time


def update_database():
    # Input property
    inPropertypntfc = r"G:\GIS\ESRI\Staging\Survey123\Testing\New File Geodatabase.gdb\propertypnts"
    print(inPropertypntfc)

    # input survey feature class
    inSurveyfc = r"G:\GIS\ESRI\Staging\Survey123\Testing\New File Geodatabase.gdb\retailpt2"
    print(inSurveyfc)

    # Make feature layer of feature classes to allow selection
    arcpy.MakeFeatureLayer_management(inPropertypntfc, "Propertypntlyr")
    arcpy.MakeFeatureLayer_management(inSurveyfc, "Surveylyr")


    # select intersecting points
    arcpy.SelectLayerByLocation_management("Propertypntlyr", "INTERSECT", "Surveylyr")
    print ("select")

    # Update Cursor for point layer
    cursor = arcpy.da.UpdateCursor("Propertypntlyr", ["CompleteY_N"])
    print (cursor)
    for row in cursor:
        cursor.updateRow(["Completed"])
    print ("Done")

    del row
    del cursor
    
    arcpy.Delete_management("Propertypntlyr")
    arcpy.Delete_management("Surveylyr")


def all_surveys_complete():
    inPropertypntfc = r"G:\GIS\ESRI\Staging\Survey123\Testing\New File Geodatabase.gdb\propertypnts"

    # Make feature layer of feature classes to allow selection
    arcpy.MakeFeatureLayer_management(inPropertypntfc, "Propertypntlyr")

    # Select features that are not complete
    arcpy.SelectLayerByAttribute_management("Propertypntlyr", 'NEW_SELECTION',
                                             """   "CompleteY_N" <> 'Completed'  """)

    #Check if we got a selection
    desc = arcpy.Describe("Propertypntlyr")
    if desc.FIDSet  == '':
        #If there is no selection, all surveys are complete
        arcpy.Delete_management("Propertypntlyr")
        return True
    else:
        arcpy.Delete_management("Propertypntlyr")
        return False



#Main Script logic


#Carry on forever (until we "break" the loop)
while True:

    #Existing code
    update_database()

    #Check if all are complete
    if all_surveys_complete() == True:

        #Exit the while loop
        break

    #Wait for 10 mins for more surveys to be completed and added to the retailpt2 layer
    time.sleep(600)


print "All surveys are complete!"


JessicaRamirez1
New Contributor II

Thank you, I will try this out! 

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