Personal documentation for managing date & time in python/pandas. This is a living document to assist analysis projects in Jupyter Notebook.
Table of Contents:
- What is today?s date?
- Convert Datetime to Date
- Create new [?day?],[?week?],[?month?], or [?year?]column from Datetime
- Convert String to Timestamp
- Convert String to Datetime
- Convert Dataframe String Date Column to Datetime
- Strip Date String Data
- Convert Timestamp to String
- Convert String Column to Datetime
- Convert Timestamp to Datetime
- Unix Date Modifiers
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1. What is today?s date?
# gives timestamp of today’s date at the time of cell executionimport pandas as pdtoday = pd.to_datetime(‘today’)
# using timedelta on a datetime from datetime import timedeltatoday = pd.to_datetime(‘today’)last_week = today + timedelta(days=-7)# this will return a timestamp
3. Convert Datetime to Date
from datetime import datetime as dtdf[‘date’] = df[‘date_time’].dt.normalize()
4. Create new [?day?],[?week?],[?month?], or [?year?]column from Datetime
df[‘week’] = df[‘date_time’].dt.weekdf[‘month’] = df[‘date_time’].dt.monthdf[‘year’] = df[‘date_time’].dt.yeardf[‘week-year’] = df[‘date_time’].dt.strftime(‘%Y-%U’)df[‘month-year’] = df[‘date_time’].dt.strftime(‘%Y-%m’)
Another way to approach this (if you get error: Can only use .dt accessor with datetimelike values):
df[‘month’] = pd.DatetimeIndex(df[‘start_date’]).monthdf[‘year’] = pd.DatetimeIndex(df[‘start_date’]).year
5. Convert String to Timestamp
import timeimport datetimes = “01/12/2011″time_stamp = time.mktime(datetime.datetime.strptime(s, “%d/%m/%Y”).timetuple())
6. Convert String to Datetime
date_string = ‘2019-04-17’time_stamp = pd.to_datetime(date_string)date_time = time_stamp.date()
7. Convert Dataframe String Column to Datetime
df[‘datetime’] = pd.to_datetime(df.date_string)time_stamp = pd.to_datetime(date_string)date_time = time_stamp.date()
8. Strip Date String Data
date_string = ‘2020-07-26T00:00:00’df[‘date_string’].str.strip(‘T00:00:00’)
9. Convert Timestamp or Datetime to String
str(timestamp)#output will look like: ‘2019-11-02 11:26:58.924878’str(timestamp)[:-16]#output will look like: ‘2019-11-02’#then you can evalute <, >, = vs. other date stringssometimes you need to mess around with the values x & y here to get the string you want… str(timestamp)[X:Y]for example, str(timestamp)[1:18] may be required in some instances, etc.
10. Convert String Column to Datetime
df[‘date_time’] = df[‘string_date’].astype(‘datetime64[ns]’)
11. Convert Timestamp to Datetime
date_time = time_stamp.date()
12. Unix Date Modifiers
%% a literal %%a locale’s abbreviated weekday name (e.g., Sun)%A locale’s full weekday name (e.g., Sunday)%b locale’s abbreviated month name (e.g., Jan)%B locale’s full month name (e.g., January)%c locale’s date and time (e.g., Thu Mar 3 23:05:25 2005)%C century; like %Y, except omit last two digits (e.g., 20)%d day of month (e.g., 01)%D date; same as %m/%d/%y%e day of month, space padded; same as %_d%F full date; like %+4Y-%m-%d%g last two digits of year of ISO week number (see %G)%G year of ISO week number (see %V); normally useful only with %V%h same as %b%H hour (00..23)%I hour (01..12)%j day of year (001..366)%k hour, space padded ( 0..23); same as %_H%l hour, space padded ( 1..12); same as %_I%m month (01..12)%M minute (00..59)%n a newline%N nanoseconds (000000000..999999999)%p locale’s equivalent of either AM or PM; blank if not known%P like %p, but lower case%q quarter of year (1..4)%r locale’s 12-hour clock time (e.g., 11:11:04 PM)%R 24-hour hour and minute; same as %H:%M%s seconds since 1970-01-01 00:00:00 UTC%S second (00..60)%t a tab%T time; same as %H:%M:%S%u day of week (1..7); 1 is Monday%U week number of year, with Sunday as first day of week (00..53)%V ISO week number, with Monday as first day of week (01..53)%w day of week (0..6); 0 is Sunday%W week number of year, with Monday as first day of week (00..53)%x locale’s date representation (e.g., 12/31/99)%X locale’s time representation (e.g., 23:13:48)%y last two digits of year (00..99)%Y year%z +hhmm numeric time zone (e.g., -0400)%:z +hh:mm numeric time zone (e.g., -04:00)%::z +hh:mm:ss numeric time zone (e.g., -04:00:00)%:::z numeric time zone with : to necessary precision (e.g., -04, +05:30)%Z alphabetic time zone abbreviation (e.g., EDT)
- Source: http://man7.org/linux/man-pages/man1/date.1.html
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