only count unique values in python code example

Example 1: counting unique values python

df.loc[df['mID']=='A','hID'].agg(['nunique','count','size'])

Example 2: count unique values in python

words = ['a', 'b', 'c', 'a']
unique_words = set(words)             # == set(['a', 'b', 'c'])
unique_word_count = len(unique_words) # == 3