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Automatically updating variables inside a for loop

Question asked by octaffle on Jun 10, 2015
Latest reply on Jun 12, 2015 by jmward

This question is back to basics; I looked around for an answer or a clue and I can't find what I'm looking for.  I'm stuck.

 

I've got 3 variables with assigned string values (shapefile paths) and I am running them through a loop to check that their projected coordinate systems (PCS) are the same as my DEM's PCS.  I want the code to check if they're the same, and if not, I want to project the file and reassign the projected file path to the original variable.

 

This is my code:

 

print("Verifying that coordinate systems are the same...")
InSHP = [outline, DA, soil]
DEMSR = arcpy.Describe(DEM).spatialReference.PCSCode
for i, l in enumerate(InSHP):
    print InSHP[i]
    sr = arcpy.Describe(l).spatialReference.PCScode
    if sr != DEMSR:
        l = arcpy.Project_management(l, l[:-4] + "PRJ.shp", DEMSR)
        InSHP[i] = l
        print InSHP[i]
print outline

 

print InSHP[i] produces the modified file path but print outline does not.

 

So, l = the projected shapefile but the l doesn't automatically connect the original variable name (outline) to the new path.  I was initially expecting the program to automatically deduce that l = new path = outline, which was kind of stupid of me to think in retrospect.  Now I explicitly know that l only refers to the entry in the list and is in no way connected to the original variable aside from having the same starting values.  Is there a way to automate this sort of assignment or am I doomed to adding the following at the end of my code?

 

outline = InSHP[0]
DA = InSHP[1]
soil = InSHP[2]

 

I guess it's not a big deal because there's only 3 of them but what if I need to check more inputs?

 

As a side question, this loop tells me that my soils file does not have a PCS, but when I look at the file properties in GIS or Catalog, it does have a PCS.  Any idea why that's happening?

 

EDIT: Ugh.  Adding those next 3 lines at the end didn't actually accomplish what I wanted it to accomplish.  I'm so used to working with cursors and GIS tables that my plain list skills are lacking. :S

 

EDIT 2: Okay I got my list to update using the enumerate function and I updated my code accordingly.  My original question(s) still stand, though.  Is there a way to assign the new values to the original variables names without having to explicitly type the variable names again?  I'm starting to think there isn't but I already posted this and I'm going to keep it here in case any other novice has this same problem. 

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