Python defaultdict(list)

>>> s = [('yellow', 1), ('blue', 2), ('yellow', 3), ('blue', 4), ('red', 1)]
>>> d = defaultdict(list)
>>> for k, v in s:
...     d[k].append(v)
...
>>> d.items()
[('blue', [2, 4]), ('red', [1]), ('yellow', [1, 3])]

Source: docs.python.org

.defaultdict

>>> from collections import defaultdict
>>> food_list = 'spam spam spam spam spam spam eggs spam'.split()
>>> food_count = defaultdict(int) # default value of int is 0
>>> for food in food_list:
...     food_count[food] += 1 # increment element's value by 1
...
defaultdict(<type 'int'>, {'eggs': 1, 'spam': 7})
>>>

Source: accelebrate.com

Similar codes

15 votes105 views3 answers
Python - gropuby based on 2 variabels
Python
1 vote150 views1 answer
Python groupby sum single columns
Python
15 votes120 views3 answers
Divide list into equal parts python
Python
1 vote92 views1 answer
Installing more modules in pypy
Python
0 vote147 views1 answer
Python update flask
Python Flask
0 vote113 views1 answer
Boto3 cross region
Python
0 vote96 views2 answers
Django rest framework foreign key relation giving error in serializer
Python
0 vote94 views1 answer
Foreign key django createview
Python
0 vote102 views1 answer
Compute slice distance from image position
Python
2 votes107 views2 answers
Requests sessions
Python