.. _chshdatesrst:

====================
Cheat Sheet on dates
====================


.. only:: html

    **Links:** :download:`notebook <chsh_dates.ipynb>`, :downloadlink:`html <chsh_dates2html.html>`, :download:`PDF <chsh_dates.pdf>`, :download:`python <chsh_dates.py>`, :downloadlink:`slides <chsh_dates.slides.html>`, :githublink:`GitHub|_doc/notebooks/cheat_sheets/chsh_dates.ipynb|*`


Cheat sheet on dates.

.. code:: ipython3

    from jyquickhelper import add_notebook_menu
    add_notebook_menu()






.. contents::
    :local:





string to datetime and datetime to string
-----------------------------------------

see `how to convert a string date into datetime format in
python <http://stackoverflow.com/questions/19068269/how-to-convert-a-string-date-into-datetime-format-in-python>`__

.. code:: ipython3

    import datetime
    d = datetime.datetime.strptime("11/08/75", "%d/%m/%y")
    d




.. parsed-literal::
    datetime.datetime(1975, 8, 11, 0, 0)



.. code:: ipython3

    d.strftime("%Y-%m-%d")




.. parsed-literal::
    '1975-08-11'



now, time difference
--------------------

.. code:: ipython3

    from datetime import datetime
    now = datetime.now()
    now




.. parsed-literal::
    datetime.datetime(2017, 11, 9, 11, 30, 20, 895311)



.. code:: ipython3

    delta = now - datetime(now.year - 1, 12, 31)
    delta




.. parsed-literal::
    datetime.timedelta(313, 41452, 134562)



.. code:: ipython3

    delta.days




.. parsed-literal::
    313



day of the year
---------------

.. code:: ipython3

    now = datetime.now()
    now




.. parsed-literal::
    datetime.datetime(2017, 11, 9, 11, 31, 7, 946012)



.. code:: ipython3

    day_of_year = now.timetuple().tm_yday
    day_of_year




.. parsed-literal::
    313