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#Python Dictionary only contain one key : one value pair.
#You can surely have multiple keys having same value
#Example :-
dict = {'a':'value1', 'b':'value2', 'c':'value 3'}
#In above we have a and b key having same values
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No, each key in a dictionary should be unique.
You can’t have two keys with the same value.
Attempting to use the same key again will just overwrite the previous value stored.
If a key needs to store multiple values,
then the value associated with the key should be a list or another dictionary.
Sourece: https://discuss.codecademy.com/t/can-a-dictionary-have-two-keys-of-the-same-value/351465
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from collections import defaultdict
data = [(2010, 2), (2009, 4), (1989, 8), (2009, 7)]
d = defaultdict(list)
print (d) # output --> defaultdict(<type 'list'>, {})
for year, month in data:
d[year].append(month)
print (d) # output --> defaultdict(<type 'list'>, {2009: [4, 7], 2010: [2], 1989: [8]})
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>>> from collections import defaultdict
>>> data = [(2010, 2), (2009, 4), (1989, 8), (2009, 7)]
>>> d = defaultdict(list)
>>> d
defaultdict(<type 'list'>, {})
>>> for year, month in data:
d[year].append(month)
>>> d
defaultdict(<type 'list'>, {2009: [4, 7], 2010: [2], 1989: [8]})
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from collections import defaultdict
unigrams = defaultdict(int)
for word in corpus:
unigrams[word] += 1