Python : how to find the frequency(count) of each element of a list or array?

Question

Is there any function to find the frequency of each element present in a list or Numpy array? I can write a code small code for this, but I need some function if there exists any.

Answer 1

You can use either numpy.unique() or scipy.stats.itemfreq() to find the frequency of list items. Have a look at the following examples.

Approach 1

>>> b
array([2, 1, 2, 0, 2, 1, 2, 1, 2, 1, 2], dtype=int64)
>>> import scipy
>>> scipy.stats.itemfreq(b)
array([[0, 1],
       [1, 4],
       [2, 6]], dtype=int64)

Approach 2

>>> val,count=np.unique(b,return_counts=True)
>>> print np.asarray((val,count)).T
[[0 1]
 [1 4]
 [2 6]]