Value add to the wrong key in a dictionary

[malbianco]

BPO	38984
Nosy	@ericvsmith, @malbianco, @0xcurb
Files	program.py programTEST.py

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = <Date 2019-12-06.10:21:46.984>
created_at = <Date 2019-12-06.00:22:50.111>
labels = ['type-bug', 'invalid']
title = 'Value add to the wrong key in a dictionary'
updated_at = <Date 2019-12-06.10:21:46.983>
user = 'https://github.com/malbianco'

bugs.python.org fields:

activity = <Date 2019-12-06.10:21:46.983>
actor = 'christian.heimes'
assignee = 'none'
closed = True
closed_date = <Date 2019-12-06.10:21:46.984>
closer = 'christian.heimes'
components = []
creation = <Date 2019-12-06.00:22:50.111>
creator = 'malbianco'
dependencies = []
files = ['48759', '48760']
hgrepos = []
issue_num = 38984
keywords = []
message_count = 4.0
messages = ['357894', '357895', '357898', '357900']
nosy_count = 3.0
nosy_names = ['eric.smith', 'malbianco', 'ramahmed']
pr_nums = []
priority = 'normal'
resolution = 'not a bug'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue38984'
versions = ['Python 3.6']

[malbianco]

hello,
I found this strange issue in my program:

I’m reading a file with 5 columns separated by ‘;’ . Columns 3,4 and 5 can have multiple values and in this case, are separated by ‘,’ .
Some values in column 3 can be repeated in each line in the same column.

Goal:
I want create a dictionary for each line using as a key the value in the first column and another key using the values that are in column 3.
If the key in column 3 is already in the dictionary, I want add the value in column 4 to the dictionary for the key that is repeated.

Example file:
col1;col2;col3;col4;col5
id1;i1;val1;Si1;Da1
id2;i2;val2,val1;Si2,Si1;Da2
id3;i3;val3;Si3;Da3

Expected Result:
{‘id1’ : [ 'id1','i1',['val1'],['Si1'],['Da1’] ] ,
‘id2’ : [‘ id2','i2',['val2','val1'] ,[Si2,Si1] ,['Da2’] ] ,
‘val1’ : [ 'id1','i1',['val2','val1'],['Si2','Si1'],['Da1','Da2’] ] ,
‘val2’ : [ 'id2','i2',['val2','val1'],[Si2,Si1] ,['Da2’] ] ,
'id3’ : [ 'id3','i3','val3',['Si3'],['Da3’] ] ,
‘val3’ : [ 'id3','i3','val3',['Si3'],['Da3’] ] }

But what I obtaining is
{'id2': ['id2', 'i2', ['val2', 'val1'], ['Si2', 'Si1'], ['Da2'], '5'],
'id3': ['id3', 'i3', ['val3'], ['Si3'], ['Da3'], '5’],
'id1': ['id1', 'i1', ['val1'], ['Si1', 'Si2', 'Si1'], ['Da1', 'Da2'], '5'],
'val3': ['id3', 'i3', ['val3'], ['Si3'], ['Da3'], '5'],
'val2': ['id2', 'i2', ['val2', 'val1'], ['Si2', 'Si1'], ['Da2'], '5'],
'val1': ['id1', 'i1', ['val1'], ['Si1', 'Si2', 'Si1'], ['Da1', 'Da2'], '5']}

My bug:
Key id1 was called just one time in my program, but in my results, I can find that list in position 3 is with 3 value (Si1 , Si2 , Si1) when it supposes to have just Si1.

Am I doing something wrong or this is a potential bug?
I ran the program using a different machines and different python versions, but results don't change.

[ericvsmith]

This is almost certainly not a bug in Python.

The bug tracker isn't for giving help with your code. I suggest you ask on the python-list mailing list https://mail.python.org/mailman/listinfo/python-list

If you still think this is a bug in Python, you should create a simpler program to reproduce the problem, and one that doesn't use any third-party code.

[malbianco]

Hi Eric,
I think is a bug and not a simple coding error.
python is adding new value into another key in a dictionary when the key is not called.
I updated my code (check "programTEST.py") that can replicate perfectly my problem.

Please try my program and let me know if you think is a bug or a "coding" error.

[0xcurb]

It's a bug in your code.

masterInfoDict['id1'][4] and masterInfoDict['val1'][4] point to the same list object ['Si1'], to which 'Si2' and 'Si1' get appended when col1ID='id2'.