Python | Pandas.factorize()

# importing libraries
import numpy as np
import pandas as pd
from pandas.api.types import CategoricalDtype

labels, uniques = pd.factorize(['b', 'd', 'd', 'c', 'a', 'c', 'a', 'b'])

print("Numeric Representation : \n", labels)
print("Unique Values : \n", uniques)

# sorting the numerics
label1, unique1 = pd.factorize(['b', 'd', 'd', 'c', 'a', 'c', 'a', 'b'], 
                                                           sort = True)

print("\n\nNumeric Representation : \n", label1)
print("Unique Values : \n", unique1)

# Missing values indicated
label2, unique2 = pd.factorize(['b', None, 'd', 'c', None, 'a', ], 
                                              na_sentinel = -101)

print("\n\nNumeric Representation : \n", label2)
print("Unique Values : \n", unique2)

# When factorizing pandas object; unique will differ 
a = pd.Categorical(['a', 'a', 'c'], categories =['a', 'b', 'c'])

label3, unique3 = pd.factorize(a)

print("\n\nNumeric Representation : \n", label3)
print("Unique Values : \n", unique3)