Python List Issue

[Aggie64]

1. create a list named All_Items_List
2. set All_Items_List_Copy = All_Items_List
3. create Subset_list which has one less item than All_Items_List and All_Items_List_Copy
4. remove all items from All_Items_List_Copy that exist in Subset_List
5 result is all items removed from All_Items_List_Copy are also removed from All_Items_List

I thought that after setting All_Items_List_Copy= All_Items_List, that All_Items_List_Copy would be separate from All_Items_List

Below is the code used:

All_Items_List = ["a","b","c","d","e","f","g","h"]
All_Items_List_Copy=All_Items_List
Subset_List =  ["a","b","c","d","e","f","g"]  #  "h" is missing from subset list

print("All_Items_List      = ",All_Items_List )
print("All_Items_List_Copy = ",All_Items_List_Copy)
print("Subset_List         = ",Subset_List)
print(" ")

for items in Subset_List :
    All_Items_List_Copy.remove(items)

print("All_Items_List     = ",All_Items_List )
print("All_Items_List_Copy = ",All_Items_List_Copy)
print("Subset_List         = ",Subset_List)

Output from the code:
All_Items_List      =  ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h']
All_Items_List_Copy =  ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h']
Subset_List         =  ['a', 'b', 'c', 'd', 'e', 'f', 'g']  # "h" is missing from the Subset_List
 
All_Items_List      =  ['h']
All_Items_List_Copy =  ['h']
Subset_List         =  ['a', 'b', 'c', 'd', 'e', 'f', 'g']

why does removing items from the All_Items_List_Copy also remove the same items from All_Items_List ?

Yoriz write Jun-29-2022, 03:42 PM:
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