1. data-science-ipython-notebooks
  2. python-data

This notebook was prepared by Donne Martin. Source and license info is on GitHub.

Dates and Times

  • Basics
  • strftime
  • strptime
  • timedelta

Basics

In [1]:
from datetime import datetime, date, time
In [2]:
year = 2015
month = 1
day = 20
hour = 7
minute = 28
second = 15
In [3]:
dt = datetime(year, month, day, hour, minute, second)
In [4]:
dt.hour, dt.minute, dt.second
Out[4]:
(7, 28, 15)

Extract the equivalent date object:

In [5]:
dt.date()
Out[5]:
datetime.date(2015, 1, 20)

Extract the equivalent time object:

In [6]:
dt.time()
Out[6]:
datetime.time(7, 28, 15)

When aggregating or grouping time series data, it is sometimes useful to replace fields of a series of datetimes such as zeroing out the minute and second fields:

In [7]:
dt.replace(minute=0, second=0)
Out[7]:
datetime.datetime(2015, 1, 20, 7, 0)

strftime

Format a datetime string:

In [8]:
dt.strftime('%m/%d/%Y %H:%M')
Out[8]:
'01/20/2015 07:28'

strptime

Convert a string into a datetime object:

In [9]:
datetime.strptime('20150120', '%Y%m%d')
Out[9]:
datetime.datetime(2015, 1, 20, 0, 0)

timedelta

Get the current datetime:

In [10]:
dt_now = datetime.now()

Subtract two datetime fields to create a timedelta:

In [11]:
delta = dt_now - dt
delta
Out[11]:
datetime.timedelta(6, 40171, 885211)

Add a datetime and a timedelta to get a new datetime:

In [12]:
dt + delta
Out[12]:
datetime.datetime(2015, 1, 26, 18, 37, 46, 885211)