Counting the number of occurrences in Python

Question

I have a list with 0, 1 and 2, I want to create a dict with the count of each. This is my code,

count_map = {}
for i in my_list:
  if i in count_map:
     count_map[i] += 1
  else:
     count_map[i] = 1

My question is how can I write this code more pythonically.

has anyone been able to decide whether questions like these should be answered by an answer or a comment? I am still struggling — Ma0, Jul 19 '17 at 15:34
I'm new to Python and trying to learn the style guidelines, is SO only for advanced users? — Melissa Stewart, Jul 19 '17 at 15:35

Mohd · Answer 1 · 2017-07-19T15:39:12.790

6

You can use collections.Counter to do that for you:

from collections import Counter
count_map = Counter(my_list)

You can type cast it to dictionary by using dict(Counter(my_list))

edited Jul 19 '17 at 15:39

answered Jul 19 '17 at 15:33

Mohd

score 2 · Answer 2 · answered Jul 19 '17 at 15:35

2

I would increment value in your dictionary this way in one line:

count_map = {}
for i in my_list:
  count_map[i] = count_map.get(i,0) + 1

answered Jul 19 '17 at 15:35

OLIVER.KOO

khelili miliana · Answer 3 · 2017-07-19T15:48:18.767

1

Using a dict cmprh :

l=[1,1,1,2,1,2,5,4,2,5,1,4,5,2]
{i:l.count(i) for i in set(l)}

Output :

{1: 5, 2: 4, 4: 2, 5: 3}

edited Jul 19 '17 at 15:48

answered Jul 19 '17 at 15:35

khelili miliana

3 Answers3