Why the nested dictionary cannot append into list correctly?

user_13665003 0
Viewed 39

I try to append a dictionary into a list, but I find the sub-dictionary is always keep the last one I read from CSV file(deviceProfile.csv). Does anyone know why? Here is my CSV file. 

name,description,primaryTable,startingAddress,boolIndex
test_name_1,1,table_1,1,1
test_name_2,2,table_2,2,2
test_name_3,3,table_3,3,3

Here is my python code. 

import csv
import yaml
from pprint import pprint

resource = {
    'name': "",
    'description': "",
    'attributes':
      { 'primaryTable': "", 'startingAddress': "", 'boolIndex': "" },
}

resourceArray = []

with open("deviceProfile.csv") as f:
    myCsvDic = csv.DictReader(f)
    for row in myCsvDic:
        resource['name'] = row['name']
        resource['description'] = row['description']
        resource['attributes']['primaryTable'] = row['primaryTable']
        resource['attributes']['startingAddress'] = row['startingAddress']
        resource['attributes']['boolIndex'] = row['boolIndex']
        test = resource.copy()
        resourceArray.append(test)

pprint (resourceArray)

And the result is

[{'attributes': {'boolIndex': '3',
                 'primaryTable': 'table_3',
                 'startingAddress': '3'},
  'description': '1',
  'name': 'test_name_1'},
 {'attributes': {'boolIndex': '3',
                 'primaryTable': 'table_3',
                 'startingAddress': '3'},
  'description': '2',
  'name': 'test_name_2'},
 {'attributes': {'boolIndex': '3',
                 'primaryTable': 'table_3',
                 'startingAddress': '3'},
  'description': '3',
  'name': 'test_name_3'}]

It is strange that name and description are appended into list correctly, but attributes. The attributes is always append the last sub-dictionary.

Any help will be appreciated. Thanks.

append list dictionary python
2 Answers

This is because of copy. by default copy is shallow copy and it will copy just level-1 elements. you should use deepcopy in your case. replace test = resource.copy() with:

from copy import deepcopy

test = deepcopy(resource)

take a look at this Link for more information, or any other links that tells you about copy(shallow and deep).

user_37447470

Why do you have resource on the top outside the loop ??? 

resource = {
    'name': "",
    'description': "",
    'attributes':
      { 'primaryTable': "", 'startingAddress': "", 'boolIndex': "" },
}

Remove that and just change the loop to this :

for row in myCsvDic:
    resource = {}
    resource['name'] = row['name']
    resource['description'] = row['description']
    resource['attributes']['primaryTable'] = row['primaryTable']
    resource['attributes']['startingAddress'] = row['startingAddress']
    resource['attributes']['boolIndex'] = row['boolIndex']
    resourceArray.append(resource)
user_64907440
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