Extract month and year from column in Pandas, create new column

import modules

import pandas as pd
import numpy as np
import datetime

create dummy dataframe

raw_data = {'name': ['Willard Morris', 'Al Jennings', 'Omar Mullins', 'Spencer McDaniel'],
'age': [20, 19, 22, 21],
'favorite_color': ['blue', 'red', 'yellow', "green"],
'grade': [88, 92, 95, 70],
'birth_date': ['01-02-1996', '08-05-1997', '04-28-1996', '12-16-1995']}
df = pd.DataFrame(raw_data, index = ['Willard Morris', 'Al Jennings', 'Omar Mullins', 'Spencer McDaniel'])
df

	age	birth_date	favorite_color	grade	name
Willard Morris	20	01-02-1996	blue	88	Willard Morris
Al Jennings	19	08-05-1997	red	92	Al Jennings
Omar Mullins	22	04-28-1996	yellow	95	Omar Mullins
Spencer McDaniel	21	12-16-1995	green	70	Spencer McDaniel

create a new column with year of date field 'birth_date'

#pandas datetimeindex docs: https://pandas.pydata.org/pandas-docs/stable/generated/pandas.DatetimeIndex.html
#efficient way to extract year from string format date
df['year'] = pd.DatetimeIndex(df['birth_date']).year
df.head()

	age	birth_date	favorite_color	grade	name	year
Willard Morris	20	01-02-1996	blue	88	Willard Morris	1996
Al Jennings	19	08-05-1997	red	92	Al Jennings	1997
Omar Mullins	22	04-28-1996	yellow	95	Omar Mullins	1996
Spencer McDaniel	21	12-16-1995	green	70	Spencer McDaniel	1995

create a new column with month of date field 'birth_date'

#pandas datetimeindex docs: https://pandas.pydata.org/pandas-docs/stable/generated/pandas.DatetimeIndex.html
df['month'] = pd.DatetimeIndex(df['birth_date']).month
df.head()

	age	birth_date	favorite_color	grade	name	year	month
Willard Morris	20	01-02-1996	blue	88	Willard Morris	1996	1
Al Jennings	19	08-05-1997	red	92	Al Jennings	1997	8
Omar Mullins	22	04-28-1996	yellow	95	Omar Mullins	1996	4
Spencer McDaniel	21	12-16-1995	green	70	Spencer McDaniel	1995	12

#if the date format comes in datetime, we can also extract the day/month/year using the to_period function
#where 'D', 'M', 'Y' are inputs
df['month_year'] = pd.to_datetime(df['birth_date']).dt.to_period('M')
df.head()

	age	birth_date	favorite_color	grade	name	year	month	month_year
Willard Morris	20	01-02-1996	blue	88	Willard Morris	1996	1	1996-01
Al Jennings	19	08-05-1997	red	92	Al Jennings	1997	8	1997-08
Omar Mullins	22	04-28-1996	yellow	95	Omar Mullins	1996	4	1996-04
Spencer McDaniel	21	12-16-1995	green	70	Spencer McDaniel	1995	12	1995-12