series count_value code example
Example 1: count values pandas
>>> index = pd.Index([3, 1, 2, 3, 4, np.nan])
>>> index.value_counts()
3.0 2
4.0 1
2.0 1
1.0 1
dtype: int64
Example 2: relativefrequencies of the unique values pandas
df.value_counts(normalize=True)