This piece of code is giving me an error unhashable type: dict can anyone explain me what is the solution
negids = movie_reviews.fileids('neg') def word_feats(words): return dict([(word, True) for word in words]) negfeats = [(word_feats(movie_reviews.words(fileids=[f])), 'neg') for f in negids] stopset = set(stopwords.words('english')) def stopword_filtered_word_feats(words): return dict([(word, True) for word in words if word not in stopset]) result=stopword_filtered_word_feats(negfeats)
You're trying to use a dict as a key to another dict or in a set. That does not work because the keys have to be hashable. As a general rule, only immutable objects (strings, integers, floats, frozensets, tuples of immutables) are hashable (though exceptions are possible). So this does not work:
>>> dict_key = {"a": "b"} >>> some_dict[dict_key] = True Traceback (most recent call last): File "", line 1, in TypeError: unhashable type: 'dict'
To use a dict as a key you need to turn it into something that may be hashed first. If the dict you wish to use as key consists of only immutable values, you can create a hashable representation of it like this:
>>> key = frozenset(dict_key.items())
Now you may use key as a key in a dict or set:
>>> some_dict[key] = True >>> some_dict {frozenset([('a', 'b')]): True}
Of course you need to repeat the exercise whenever you want to look up something using a dict:
>>> some_dict[dict_key] # Doesn't work Traceback (most recent call last): File "", line 1, in TypeError: unhashable type: 'dict' >>> some_dict[frozenset(dict_key.items())] # Works True
If the dict you wish to use as key has values that are themselves dicts and/or lists, you need to recursively "freeze" the prospective key. Here's a starting point:
def freeze(d): if isinstance(d, dict): return frozenset((key, freeze(value)) for key, value in d.items()) elif isinstance(d, list): return tuple(freeze(value) for value in d) return d
