python - How to convert Counter object to dict?

Question

Data frame:

pair = collections.defaultdict(collections.Counter)

e.g.

pair = {'doc1':  {'word1':4, 'word2':3}, 
        'doc2':  {'word1':2, 'word3':4},
        'doc3':  {'word2':2, 'word4':1},
         ...}

I want to keep the data frame but alter the type of this part {'word1':4, 'word2':3} {'word1':2, 'word3':4}``... It is now a Counter and I need a dict.

I tried this to get the data from pair, but I do not know how to create a dict for each doc:

new_pair = collections.defaultdict(collections.Counter)
for doc, tab in testing.form.items():
    for word, freq in tab.items():
        new_pair[doc][word] = freq 

I do not want to change the output. I just need that in each doc, the data type is dict, not Counter.

Answer 1

A Counter is already a dict - or, a subclass of it. But, if you really need exactly a dict for some reason, then its a one-liner:

>>> c = Counter(word1=4, word2=3)
>>> c
Counter({'word1': 4, 'word2': 3})
>>> dict(c)
{'word1': 4, 'word2': 3}

Any Mapping (anything that behaves like a dictionary) can be passed into dict, and you will get a dict with the same contents. There is no need to iterate over it to construct it yourself.

This gives you one loop, with one line in the body instead of a nested loop. But any code of the form:

 thing = a new empty collection
 for elem in old_thing:
    Add something to do with elem to thing

Can usually be done in one line using a generator expression or a list, set or dict comprehension. We're building a dict, so a dict comprehension (the Examples section is what you're most interested in) seems likely. I'll leave coming up with it as an exercise for the reader. ;-)