具有列表值的字典键

Question

I wanted to append to respective keys in a dictionary in the list of string

myDictionary = {'johny': [], 'Eli': [], 'Johny': [], 'Jane': [], 'john': [], 'Ally': []}

votes = ['johny', 'Eli', 'Eli', 'Jane', 'Ally', 'Johny', 'john', 'Eli']

outPut={'johny': ['johny'], 'Eli': ['Eli','Eli'], 'Johny': ['Johny'], 'Jane': ['Jane'], 'john': ['john'], 'Ally': ['Ally']}

I tried to do like this but appends the whole list in each key

votes_dictionary={}
votes_dictionary=votes_dictionary.fromkeys(votes,[])
for i in votes:
    print(i.lower())
    votes_dictionary[i].append(i)
print(votes_dictionary)

Answer 1

You can use defaultdict with list as default value and then iterate through votes and append it:

from collections import defaultdict

votes = ['johny', 'Eli', 'Eli', 'Jane', 'Ally', 'Johny', 'john', 'Eli']
votes_dictionary = defaultdict(list)

for vote in votes:
    votes_dictionary[vote].append(vote)


# votes_dictionary will be an instance of defaultdict
# to convert it to dict, just call dict
print(dict(votes_dictionary))


# outpout
{'johny': ['johny'], 'Eli': ['Eli', 'Eli', 'Eli'], 'Jane': ['Jane'], 'Ally': ['Ally'], 'Johny': ['Johny'], 'john': ['john']}

Answer 2

I see there are three Eli s, so typically it would look like this:

output = {}

for name in votes:
    output.setdefault(name, [])
    output[name].append(name)
print(output)

Output:

{'johny': ['johny'],
 'Eli': ['Eli', 'Eli', 'Eli'],
 'Jane': ['Jane'],
 'Ally': ['Ally'],
 'Johny': ['Johny'],
 'john': ['john']}

Or,

import copy
output = copy.deepcopy(mydictionary)
for name in votes:
    output[name].append(name)
print(output):

output:

{'johny': ['johny'],
 'Eli': ['Eli', 'Eli', 'Eli'],
 'Johny': ['Johny'],
 'Jane': ['Jane'],
 'john': ['john'],
 'Ally': ['Ally']}

Now, if you want to limit to two even if there are three elements:

output = {}
for name in votes:
# to maintain the order, you can iterate over `mydictionary`
    output[name] = [name]*min(2, votes.count(name))
print(output)

output:

{'johny': ['johny'],
 'Eli': ['Eli', 'Eli'],
 'Jane': ['Jane'],
 'Ally': ['Ally'],
 'Johny': ['Johny'],
 'john': ['john']}

Another fun way to achieve two occurrences of Eli would be, itertools.groupby :

>>> from itertools import groupby
>>> {key: [*group] for key, group in groupby(reversed(votes))}
{'Eli': ['Eli', 'Eli'],
 'john': ['john'],
 'Johny': ['Johny'],
 'Ally': ['Ally'],
 'Jane': ['Jane'],
 'johny': ['johny']}

Answer 3

votes_dictionary={}
for i in votes:
    try:
        votes_dictionary[i].append(i)
    except KeyError:
        votes_dictionary[i] = [i]
print(votes_dictionary)

Answer 4

myDictionary = {'johny': [], 'Eli': [], 'Johny': [], 'Jane': [], 'john': [], 'Ally': []}

votes = ['johny', 'Eli', 'Eli', 'Jane', 'Ally', 'Johny', 'john', 'Eli']

for x in votes:
   myDictionary[x].append(x)

Answer 5

votes_dictionary = {}
votes_dictionary = votes_dictionary.fromkeys(votes)
for i in votes:
    if not votes_dictionary[i]:
        votes_dictionary[i] = []
    votes_dictionary[i].append(i)
print(votes_dictionary)

A lot of answers have been posted, if you really want to use the fromkeys() method, you could do something like this