How to count occurrences of specific dict key in list of dicts

Question

I'm trying to count the number of times a specified key occurs in my list of dicts. I've used Counter() and most_common(n) to count up all the keys, but how can I find the count for a specific key? I have this code, which does not work currently:

def Artist_Stats(self, artist_pick):

    entries = TopData(self.filename).data_to_dict()

    for d in entries:
        x = d['artist']
        find_artist = Counter()
        print find_artist[x][artist_pick]

The "entries" data has about 60k entries and looks like this:

[{'album': 'Nikki Nack', 'song': 'Find a New Way', 'datetime': '2014-12-03 09:08:00', 'artist': 'tUnE-yArDs'},]

Answer 1

You could extract it, put it into a list, and calculate the list's length.

key_artists = [k['artist'] for k in entries if k.get('artist')]
len(key_artists)

Edit: using a generator expression might be better if your data is big:

key_artists = (1 for k in entries if k.get('artist'))
sum(key_artists)

2nd Edit:

for a specific artist, you would replace if k.get('artist') with if k.get('artist') == artist_pick

3rd Edit: you could loop as well, if you're not comfortable with comprehensions or generators, or if you feel that enhances code readability

n = 0  # number of artists

for k in entries:
  n += 1 if k.get('artist') == artist_pick else 0