🐥 TIL: counting values in an array

Today, I learned about the Counter class in Python.

The idea was that I had a list of dates (after parsing a log file) and I needed to count the number of occurrences of each date in that list.

The list looked something like this:

data = ['2023-02-17',
 '2023-02-17',
 '2023-02-17',
 '2023-02-17',
 '2023-02-17',
 '2023-02-17',
 '2023-02-17',
 '2023-02-18',
 '2023-02-18',
 '2023-02-18',
 '2023-02-18',
 '2023-02-18',
 '2023-02-18',
 '2023-02-18',
 '2023-02-18',
 '2023-02-20',
 '2023-02-20',
 '2023-02-20',
 '2023-02-20',
 '2023-02-20',
 '2023-02-20',
 '2023-02-20',
 '2023-02-20',
 '2023-02-20',
 '2023-02-20',
 '2023-02-20',
 '2023-02-20',
 '2023-02-20',
 '2023-02-20',
 '2023-02-20',
 '2023-02-22',
 '2023-02-22',
 '2023-02-22',
 '2023-02-22',
 '2023-02-22',
 '2023-02-22',
 '2023-02-22',
 '2023-02-22',
 '2023-02-22',
 '2023-02-22',
 '2023-02-22',
 '2023-02-22',
 '2023-02-22',
 '2023-02-22',
 '2023-02-22',
 '2023-02-22',
 '2023-02-22',
 '2023-02-22',
 '2023-02-22',
 '2023-02-22',
 '2023-02-23',
 '2023-02-23',
 '2023-02-23',
 '2023-02-23',
 '2023-02-23',
 '2023-02-23',
 '2023-02-23',
 '2023-02-23',
 '2023-02-23',
 '2023-02-23',
 '2023-02-23',
 '2023-02-23',
 '2023-02-23',
 '2023-02-27',
 '2023-02-27',
 '2023-02-27',
 '2023-02-27',
 '2023-02-27',
 '2023-03-02',
 '2023-03-02',
 '2023-03-02',
 '2023-03-02',
 '2023-03-02',
 '2023-03-03',
 '2023-03-03',
 '2023-03-03',
 '2023-03-03',
 '2023-03-03',
 '2023-03-03',
 '2023-03-03',
 '2023-03-08',
 '2023-03-08',
 '2023-03-08',
 '2023-03-08',
 '2023-03-08',
 '2023-03-08',
 '2023-03-16',
 '2023-03-16',
 '2023-03-16',
 '2023-03-16']

Using the Counter class, this becomes a very trivial task:

from collections import Counter

counts = Counter(data)

for i in counts:
    print(i, counts[i])

## Output
# 2023-02-17 7
# 2023-02-18 8
# 2023-02-20 15
# 2023-02-22 20
# 2023-02-23 13
# 2023-02-27 5
# 2023-03-02 5
# 2023-03-03 7
# 2023-03-08 6
# 2023-03-16 4