Is there a "freq" function in numpy/python? [duplicate]

Question

Suppose you have:

arr = np.array([1,2,1,3,3,4])

Is there a built in function that returns the most frequent element?

Answer 1

Yes, Python's collections.Counter has direct support for finding the most frequent elements:

>>> from collections import Counter

>>> Counter('abracadbra').most_common(2)
[('a', 4), ('r', 2)]

>>> Counter([1,2,1,3,3,4]).most_common(2)
[(1, 2), (3, 2)]

With numpy, you might want to start with the histogram() function or the bincount() function.

With scipy, you can search for the modal element with mstats.mode.

Answer 2

the pandas module might also be of help here. pandas is a neat data analysis package for python and also has support for this problem.

import pandas as pd 
arr = np.array([1,2,1,3,3,4])
arr_df = pd.Series(arr) 
value_counts = arr_df.value_counts()
most_frequent = value_counts.max()

this returns

> most_frequent 
2