/Python/Append to a ldictionary value list

Append to a ldictionary value list

#list.append returns None, since it is an in-place operation and you are 
#assigning it back to dic[key]. So, the next time when you do 
#dic.get(key, []).append you are actually doing None.append. 
#That is why it is failing. Instead, you can simply do
dates_dict.setdefault(key, []).append(date)
#or 
from collections import defaultdict
dates_dict = defaultdict(list)
for key, date in cur:
    dates_dict[key].append(date)

Source: stackoverflow.com

Similar codes

1 vote301 views2 answers
Boto3 delete bucket object
Python
0 vote295 views1 answer
Get a colomn of csv in pandas
Python
1 vote288 views1 answer
How to minimize command console python
Python
2 votes277 views5 answers
Check boolean python
Python
0 vote316 views1 answer
Creating sub elements in xml in python with ElementTree
Python
3 votes271 views1 answer
Python run a system command
Python
10 votes286 views1 answer
Print first dictionary keys python
Python
0 vote294 views1 answer
Django rest framework default_authentication_classes
Python
8 votes315 views4 answers
Remove nan from list python
Python
3 votes305 views2 answers
Python multiply list by scalar
Python