DateTime Operations

Add or Subtract Days

code.py

import pandas as pd

df = pd.DataFrame({
    'Order_Date': pd.to_datetime(['2024-01-15', '2024-02-20'])
})

# Add 7 days
df['Delivery_Date'] = df['Order_Date'] + pd.Timedelta(days=7)

print(df)

Output:

  Order_Date Delivery_Date
0 2024-01-15    2024-01-22
1 2024-02-20    2024-02-27

Add Weeks, Months, Years

code.py

# Add different time units
df['Plus_1_Week'] = df['Order_Date'] + pd.Timedelta(weeks=1)
df['Plus_30_Days'] = df['Order_Date'] + pd.Timedelta(days=30)

# For months, use DateOffset
df['Plus_1_Month'] = df['Order_Date'] + pd.DateOffset(months=1)
df['Plus_1_Year'] = df['Order_Date'] + pd.DateOffset(years=1)

Find Difference Between Dates

code.py

df = pd.DataFrame({
    'Start': pd.to_datetime(['2024-01-01', '2024-02-15']),
    'End': pd.to_datetime(['2024-01-10', '2024-03-01'])
})

# Difference in days
df['Days_Between'] = (df['End'] - df['Start']).dt.days

print(df)

Output:

       Start        End  Days_Between
0 2024-01-01 2024-01-10             9
1 2024-02-15 2024-03-01            15

Calculate Age from Birthdate

code.py

df = pd.DataFrame({
    'Name': ['John', 'Sarah'],
    'Birthday': pd.to_datetime(['1990-05-15', '1985-08-20'])
})

today = pd.Timestamp.today()
df['Age'] = ((today - df['Birthday']).dt.days / 365).astype(int)

print(df)

Filter by Date

code.py

df = pd.DataFrame({
    'Date': pd.to_datetime(['2024-01-15', '2024-02-20', '2024-03-10']),
    'Sales': [100, 150, 200]
})

# Sales after February 1st
recent = df[df['Date'] > '2024-02-01']
print(recent)

Output:

        Date  Sales
1 2024-02-20    150
2 2024-03-10    200

Filter Date Range

code.py

# Sales between Jan 10 and Feb 25
start = '2024-01-10'
end = '2024-02-25'

filtered = df[(df['Date'] >= start) & (df['Date'] <= end)]
print(filtered)

Get Today's Date

code.py

# Current date and time
now = pd.Timestamp.now()
print(now)

# Just today's date
today = pd.Timestamp.today().date()
print(today)

Compare Dates

code.py

df = pd.DataFrame({
    'Due_Date': pd.to_datetime(['2024-01-15', '2024-12-31']),
    'Task': ['Past', 'Future']
})

today = pd.Timestamp.today()
df['Is_Overdue'] = df['Due_Date'] < today

print(df)

Quick Reference

Operation	Code
Add days	+ pd.Timedelta(days=7)
Add weeks	+ pd.Timedelta(weeks=2)
Add months	+ pd.DateOffset(months=1)
Add years	+ pd.DateOffset(years=1)
Difference	(date1 - date2).dt.days
Today	pd.Timestamp.today()

Key Points

pd.Timedelta() for adding days/weeks/hours
pd.DateOffset() for adding months/years
Subtract dates to get difference
.dt.days converts to number of days
Compare dates with <, >, ==
Filter dates like numbers

What's Next?

Learn about time series - data that changes over time with regular intervals.