Python list assign by value

Question

I have a list Undo and another ap, I want to save every time I modify the ap list a copy on Undo but when I save, for example on Undo[2] what I have done to ap, Undo[1] is the same as Undo[2], it looks like it assign the list ap and not the value of ap. I find a question similar and tried to assign ap[:] so it will make a copy but it didn't.

from Functionalitati import *
from Ui import *
from GlobalVr import *
Active = True
NumarApartamente = int(input("Numarul apartamentelor:"))
cntA = 0
while cntA < NumarApartamente:
 ap.append({"gaz":{}, "apa":{}, "electricitate":{}, "canalizare":{}, "altele":{}})
 cntA = cntA + 1
Undo = Undo + ap[ : ]
while Active:
 while True:
 op1 = Umenu()
 if op1 > 6 and op1 < 0:
 print(x,'Nu este o comanda valida')
 else:
 break
 if op1 == 0:
 break
 op2 = Submenu(op1)
 if op1 == 6 and UndoCont > 0:
 UndoCont = UndoCont - 1
 Undo.pop()
 ap = Undo[UndoCont]
 print (Undo)
 elif op1 == 1 and op2 == 1 :
 ap = AddCheltuiala(ap)
 Undo = Undo + ap[ : ]
 UndoCont = UndoCont + 1
 elif op1 == 1 and op2 == 2 :
 ap = ModCheltuiala(ap)
 Undo.append(ap[0:NumarApartamente - 1])
 UndoCont = UndoCont + 1
 elif op1 == 2 and op2 == 1 :
 ap = DelCheltuiala(ap)
 Undo.append(ap[0:NumarApartamente - 1])
 UndoCont = UndoCont + 1
 elif op1 == 2 and op2 == 2 : 
 ap = DelCCheltuiala(ap)
 Undo.append(ap[0:NumarApartamente - 1])
 UndoCont = UndoCont + 1
 elif op1 == 2 and op2 == 3 :
 ap = DelTip(ap,NumarApartamente)
 Undo.append(ap[0:NumarApartamente - 1])
 UndoCont = UndoCont + 1

I also tried with append and Undo = Undo + ap[:] as you can see. Sorry if the code is a little messy. edit: I deleted last edit and I want to make it more clear So I make another piece of code to resume what I want to say

from Functionalitati import *
from Ui import *
import datetime
ap = [] #lista principala
UndoCont = 0
nrAp = int(input("Da-ti numarul apartamentelor:"))
Undo = [None] * nrAp
contor = 0
while contor < nrAp:
 ap.append({"gaz":{}, "apa":{}, "electricitate":{}, "canalizare":{}, "altele":{}})
 contor = contor + 1
Undo[0] = ap[:]
print(Undo)
print("space" * 4)
ap[1]["gaz"]["date"] = 100
Undo[1] = ap[:]
print (Undo)

the output:

Da-ti numarul apartamentelor:2
[[{'gaz': {}, 'canalizare': {}, 'electricitate': {}, 'altele': {}, 'apa': {}}, {'gaz': {}, 'canalizare': {}, 'electricitate': {}, 'altele': {}, 'apa': {}}], None]
spacespacespacespace
[[{'gaz': {}, 'canalizare': {}, 'electricitate': {}, 'altele': {}, 'apa': {}}, {'gaz': {'date': 100}, 'canalizare': {}, 'electricitate': {}, 'altele': {}, 'apa': {}}], [{'gaz': {}, 'canalizare': {}, 'electricitate': {}, 'altele': {}, 'apa': {}}, {'gaz': {'date': 100}, 'canalizare': {}, 'electricitate': {}, 'altele': {}, 'apa': {}}]]

why the Undo[0] modify as Undo[1] ? I tried with Undo.append(list(ap)) and Undo = Undo + list(ap) and same with ap[:] and now I tried to initialize Undo before and same result.

• elethan: Can you please show an example of how you want Undo to look after adding ap and an example of how it looks now?
• user7006931: ok I edited the post

Answer 1

Solved.I don't really know how it works but I use copy.deepcopy() (copy.copy() didn't work)