Count the frequency of each element categorical values in python

Question

Is there a simple way to do this in Python?

For example I have:

x = np.array(['a', 'b', 'a', 'b', 'b', 'u'])

Desired outcome:

[2, 3, 2, 3, 3, 1]

You can select an answer even after your question is closed. I'd recommend doing so, since the relatively new arguments to np.unique make the answer more efficient than the accepted one of the duplicate. — Mad Physicist, Oct 20 '19 at 03:37

Mad Physicist · Answer 1 · 2019-10-20T02:31:23.400

3

Use np.unique with return_counts and return_inverse enabled:

_, inverse, count = np.unique(x, return_inverse=True, return_count=True)
result = count[inverse]

edited Oct 20 '19 at 02:31

answered Oct 19 '19 at 14:29

Mad Physicist

1 Answers1