I am using this code to extract the genres from list of dictionaries.
dict=[{'genres': ['Thriller'], 'year': '2014'}, {'genres': ['Animation','Drama'], 'year': '2014'}]
test=[i["genres"] for i in dict]
test
[['Thriller'], ['Animation', 'Drama']]
I want to remove the inner list and create single list.
Expected output:['Thriller', 'Animation', 'Drama']
You can use a nested list comprehension to do this:
>>> list_of_dicts =[{'genres': ['Thriller'], 'year': '2014'}, {'genres': ['Animation','Drama'], 'year': '2014'}]
>>> [genre for d in list_of_dicts for genre in d['genres']]
['Thriller', 'Animation', 'Drama']
In case you have possible repeats, call set over this
>>> set(genre for d in list_of_dicts for genre in d['genres'])
{'Animation', 'Drama', 'Thriller'}
Taking cue from @mgilson's answer, if you want this to work with dicts which don't have the genres key, you can do
>>> list_of_dicts =[{'genres': ['Thriller'], 'year': '2014'}, {"year": '2014'}]
>>> set(genre for d in list_of_dicts for genre in d.get('genres', []))
{'Thriller'}
I'd use itertools.
First, write a generator that yields the genres lists (one after another).
import itertools
dicts = [{'genres': ['Thriller'], 'year': '2014'}, {'genres': ['Animation','Drama'], 'year': '2014'}]
genres_nested = (dct.get('genres', ()) for dct in dicts)
This particular generator is "forgiving" -- It'll allow for dicts in the list that don't have a 'genres' field.
Then, flatten that nested structure with itertools.chain.from_iterable (you could use a nested comprehension -- but I've always found itertools.chain.from_iterable to be easier to read ...):
genres = itertools.chain.from_iterable(genres_nested)
If you need a list, you can always call list on the resulting "chain" object...
print(list(genres))
And as a side benefit, other than this last stage, everything we've done was completely lazy -- No intermediate lists wasting storage on our computers. Yeah!
list comprehension is your friend
>>> dicts=[{'genres': ['Thriller'], 'year': '2014'}, {'genres': ['Animation','Drama'], 'year': '2014'}]
>>> [gen for d in dicts for gen in d['genres']]
['Thriller', 'Animation', 'Drama']
