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--- manipulating_dates_in_python [2021/08/14 13:17] – created raju
+++ manipulating_dates_in_python [2024/02/06 05:22] (current) – raju
@@ Line 1: / Line 1: @@
+===== Tasks =====
+  * [[Add dates]]
+    * uses | strptime
+  * [[Convert string to date]]
+===== Dummy =====
+==== date in isoformat ====
+<code>
+from datetime import date
+today = date.today().isoformat()
+print(type(today))
+print(today)
+<class 'str'>
+-09-18
+</code>
+It also works on datetime objects and will give the time in ISO 8601 format.
+<code>
+from datetime import datetime
+now = datetime.today().isoformat()
+print(type(now))
+print(now)
+<class 'str'>
+-09-18T13:55:17.214513
+</code>
+Ref:- https://stackoverflow.com/questions/32490629/getting-todays-date-in-yyyy-mm-dd-in-python
+==== extract date from datetime ====
+<code>
+$ ipython
+Python 3.10.6 | packaged by conda-forge | (main, Oct 24 2022, 16:02:16) [MSC v.1916 64 bit (AMD64)]
+Type 'copyright', 'credits' or 'license' for more information
+IPython 8.4.0 -- An enhanced Interactive Python. Type '?' for help.
+In [1]:
+from datetime import datetime
+s = '24 October 2022'
+dtt = datetime.strptime(s, "%d %B %Y")
+print(dtt)
+-10-24 00:00:00
+In [2]:
+type(dtt)
+Out[2]:
+datetime.datetime
+In [3]:
+dt = datetime.strptime(s, "%d %B %Y").date()
+print(dt)
+-10-24
+In [4]:
+type(dt)
+Out[4]:
+datetime.date
+</code>
 ==== get today's day, month and year ====
 <code>
@@ Line 23: / Line 85: @@
 [2021, 8, 14]
 </code>
+==== iterate over a range of dates ====
+To iterate on all days including weekends
+<code>
+for dt in pd.date_range('20160226', '20160303'):
+  print(dt.strftime('%Y%m%d'))
+20160226
+20160227
+20160228
+20160229
+20160301
+20160302
+20160303
+</code>
+To iterate only on weekdays
+<code>
+for dt in pd.date_range('20160226', '20160303'):
+  if (dt.weekday() < 5):
+    print(dt.strftime('%Y%m%d'))
+20160226
+20160229
+20160301
+20160302
+20160303
+</code>
+To iterate in reverse chronological order
+<code>
+for dt in pd.date_range('20160226', '20160303')[::-1]:
+  if (dt.weekday() < 5):
+    print(dt.strftime('%Y%m%d'))
+20160303
+20160302
+20160301
+20160229
+20160226
+</code>
+To experiment with just one date element
+<code>
+>>> a = pd.date_range('20160226', '20160303')
+>>> a[0].strftime('%Y%m%d')
+'20160226'
+</code>
+To create a pandas.tslib.Timestamp variable
+<code>
+>>> from datetime import datetime
+>>> for dt in pd.date_range('20160929', '20160930')[::-1]:
+...     dt == pd.Timestamp(datetime(2016, 9, 29))
+...
+False
+True
+>>> type(pd.Timestamp(datetime(2016, 9, 29)))
+<class 'pandas.tslib.Timestamp'>
+>>> for dt in pd.date_range('20160929', '20160930')[::-1]:
+...     type(dt)
+...
+<class 'pandas.tslib.Timestamp'>
+<class 'pandas.tslib.Timestamp'>
+</code>
+tags | convert output from pandas data_range function to YYYYMMDD, date_range reverse order
+Ref:-
+  * http://pandas.pydata.org/pandas-docs/stable/timeseries.html#generating-ranges-of-timestamps
+  * http://pandas.pydata.org/pandas-docs/stable/generated/pandas.date_range.html
+==== print the names of months in a year ====
+<code>
+$ ipython
+Python 3.11.4 | packaged by Anaconda, Inc. | (main, Jul  5 2023, 13:47:18) [MSC v.1916 64 bit (AMD64)]
+IPython 8.12.0 -- An enhanced Interactive Python. Type '?' for help.
+In [1]:
+import calendar
+for m in calendar.month_name:
+    print(m)
+January
+February
+March
+April
+May
+June
+July
+August
+September
+October
+November
+December
+</code>