Why after change value in dictionary, all other value also changed too?

Question

Why after change an value in specified index in dictionary, all other index value also changed, why is this happened?

with open(BotAccountFile, 'r') as account_file:
        for num, line in enumerate(account_file, 1):
            username = line.split(',')[0].strip()
            BotAccountsLinksList[num] = {'UserName': username, 'Password': line.split(',')[1].strip(),
                                         'CompletedDownload': False}

    BotLinksList = {}
    BotLinksList['LinkData'] = {}
    with open(BotDownloadURIsFile, 'r') as link_file:
        for item in BotAccountsLinksList:
            for num, line in enumerate(link_file, 1):
                BotLinksList['LinkData'][num] = {'Link': line.strip(), 'CompletedDownload': False}
            BotAccountsLinksList[item].update(BotLinksList)

And my dictionary:

BotAccountsLinksList = {}

BotAccountsLinksList = {1: {'UserName': 'user1', 'Password': 'pass1',  
    'CompletedDownload': False, 'LinkData': {1: {'Link': 'www.yahoo.com',  
    'CompletedDownload': False}, 2: {'Link': 'www.google.com',  
    'CompletedDownload': False}}}, 2: {'UserName': 'user2', 'Password': 'pass2',  
    'CompletedDownload': False, 'LinkData': {1: {'Link': 'www.yahoo.com',  
    'CompletedDownload': False}, 2: {'Link': 'www.google.com',  
    'CompletedDownload': False}}}, 3: {'UserName': 'user3', 'Password': 'pass3',  
    'CompletedDownload': False, 'LinkData': {1: {'Link': 'www.yahoo.com',  
    'CompletedDownload': False}, 2: {'Link': 'www.google.com',  
    'CompletedDownload': False}}}, 3: {'UserName': 'user4', 'Password': 'pass4',  
    'CompletedDownload': False, 'LinkData': {1: {'Link': 'www.yahoo.com',  
    'CompletedDownload': False}, 2: {'Link': 'www.google.com',  
    'CompletedDownload': False}}}}

And I use this code to change just one value in index 1:

BotAccountsLinksList[1]['LinkData'][1]['CompletedDownload'] = True # {'Link': 'www.yahoo.com', 'CompletedDownload': True}

But after running this code, other index value also changed:

BotAccountsLinksList = {1: {'UserName': 'user1', 'Password': 'pass1',  
    'CompletedDownload': False, 'LinkData': {1: {'Link': 'www.yahoo.com',  
    'CompletedDownload': True}, 2: {'Link': 'www.google.com',  
    'CompletedDownload': False}}}, 2: {'UserName': 'user2', 'Password': 'pass2',  
    'CompletedDownload': False, 'LinkData': {1: {'Link': 'www.yahoo.com',  
    'CompletedDownload': True}, 2: {'Link': 'www.google.com',  
    'CompletedDownload': False}}}, 3: {'UserName': 'user3', 'Password': 'pass3',  
    'CompletedDownload': False, 'LinkData': {1: {'Link': 'www.yahoo.com',  
    'CompletedDownload': True}, 2: {'Link': 'www.google.com',  
    'CompletedDownload': False}}}, 3: {'UserName': 'user4', 'Password': 'pass4',  
    'CompletedDownload': False, 'LinkData': {1: {'Link': 'www.yahoo.com',  
    'CompletedDownload': True}, 2: {'Link': 'www.google.com',  
    'CompletedDownload': False}}}}

I'm using Python 3.8 on Windows 10 64-bit.

@RafalS i just use that line code to change and value in an index — Pasha.A, Dec 15 '19 at 16:24
I run your code and I get correct results. If that's the whole code then this is really werid. — RafalS, Dec 15 '19 at 16:26
@RafalS Not weird at all. If you give *your mom* flowers, are you also surprised that *your brother's mom* now has flowers? They're *the same person*, just referenced differently. — Stefan Pochmann, Dec 15 '19 at 16:28
I get what a reference is, but the code uses only dict, string, number and bool literals. — RafalS, Dec 15 '19 at 16:30
@RafalS Ah, ok. Well, clearly he's not actually creating that large structure with that large literal but just presented it here like that. — Stefan Pochmann, Dec 15 '19 at 16:33
Oh, right. @PashaAleayoob, again, could you show the whole code? — RafalS, Dec 15 '19 at 16:37

score 3 · Accepted Answer · answered Dec 15 '19 at 17:00

3

BotAccountsLinksList[item].update(BotLinksList)

is doing

for k,v in BotLinksList.items():
    BotAccountsLinksList[item][k] = v

BotLinksList values will be shared across multiple BotAccountsLinksList keys. Don't reuse the same dict multiple times or do a deepcopy

import copy

BotAccountsLinksList[item].update(copy.deepcopy(BotLinksList))

answered Dec 15 '19 at 17:00

RafalS

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thanks +1 for explain.you saved my time;) – Pasha.A Dec 15 '19 at 17:22

Why after change value in dictionary, all other value also changed too?

1 Answers1