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1/5/2017 - 1:46 PM
Python.Data.DateManipulation
Python.Data.DateManipulation #python #Python #date #datetime #modules #PythonModules #datetimemodule #Dates #time #hour #second #month #year
PYTHON_DATES
# Combining Dates and Times
# Use the datetime class to hold values consisting of both date and time components. As with date, there are several convenient class methods to make creating datetime instances from other common values.
# datetime_datetime.py
import datetime
print('Now :', datetime.datetime.now())
print('Today :', datetime.datetime.today())
print('UTC Now:', datetime.datetime.utcnow())
print()
FIELDS = [
'year', 'month', 'day',
'hour', 'minute', 'second',
'microsecond',
]
d = datetime.datetime.now()
for attr in FIELDS:
print('{:15}: {}'.format(attr, getattr(d, attr)))
# As might be expected, the datetime instance has all of the attributes of both a date and a time object.
# $ python3 datetime_datetime.py
# Now : 2018-12-09 10:46:30.494767
# Today : 2018-12-09 10:46:30.494806
# UTC Now: 2018-12-09 15:46:30.494812
# year : 2018
# month : 12
# day : 9
# hour : 10
# minute : 46
# second : 30
# microsecond : 495051
# Just as with date, datetime provides convenient class methods for creating new instances. It also includes fromordinal() and fromtimestamp().
# datetime_datetime_combine.py
import datetime
t = datetime.time(1, 2, 3)
print('t :', t)
d = datetime.date.today()
print('d :', d)
dt = datetime.datetime.combine(d, t)
print('dt:', dt)
# combine() creates datetime instances from one date and one time instance.
# $ python3 datetime_datetime_combine.py
# t : 01:02:03
# d : 2018-12-09
# dt: 2018-12-09 01:02:03
#################################################################
# Comparing Values
# Both date and time values can be compared using the standard comparison operators to determine which is earlier or later.
# datetime_comparing.py
import datetime
import time
print('Times:')
t1 = datetime.time(12, 55, 0)
print(' t1:', t1)
t2 = datetime.time(13, 5, 0)
print(' t2:', t2)
print(' t1 < t2:', t1 < t2)
print()
print('Dates:')
d1 = datetime.date.today()
print(' d1:', d1)
d2 = datetime.date.today() + datetime.timedelta(days=1)
print(' d2:', d2)
print(' d1 > d2:', d1 > d2)
# All comparison operators are supported.
# $ python3 datetime_comparing.py
# Times:
# t1: 12:55:00
# t2: 13:05:00
# t1 < t2: True
# Dates:
# d1: 2018-12-09
# d2: 2018-12-10
# d1 > d2: False
#################################################################
# Date Arithmetic
# Date math uses the standard arithmetic operators.
# datetime_date_math.py
import datetime
today = datetime.date.today()
print('Today :', today)
one_day = datetime.timedelta(days=1)
print('One day :', one_day)
yesterday = today - one_day
print('Yesterday:', yesterday)
tomorrow = today + one_day
print('Tomorrow :', tomorrow)
print()
print('tomorrow - yesterday:', tomorrow - yesterday)
print('yesterday - tomorrow:', yesterday - tomorrow)
# This example with date objects illustrates using timedelta objects to compute new dates, and subtracting date instances to produce timedeltas (including a negative delta value).
# $ python3 datetime_date_math.py
# Today : 2018-12-09
# One day : 1 day, 0:00:00
# Yesterday: 2018-12-08
# Tomorrow : 2018-12-10
# tomorrow - yesterday: 2 days, 0:00:00
# yesterday - tomorrow: -2 days, 0:00:00
# A timedelta object also supports arithmetic with integers, floats, and other timedelta instances.
# datetime_timedelta_math.py
import datetime
one_day = datetime.timedelta(days=1)
print('1 day :', one_day)
print('5 days :', one_day * 5)
print('1.5 days :', one_day * 1.5)
print('1/4 day :', one_day / 4)
# assume an hour for lunch
work_day = datetime.timedelta(hours=7)
meeting_length = datetime.timedelta(hours=1)
print('meetings per day :', work_day / meeting_length)
# In this example, several multiples of a single day are computed, with the resulting timedelta holding the appropriate number of days or hours. The final example demonstrates how to compute values by combining two timedelta objects. In this case, the result is a floating point number.
# $ python3 datetime_timedelta_math.py
# 1 day : 1 day, 0:00:00
# 5 days : 5 days, 0:00:00
# 1.5 days : 1 day, 12:00:00
# 1/4 day : 6:00:00
# meetings per day : 7.0
#################################################################
# There are also class methods for creating instances from POSIX timestamps or integers representing date values from the Gregorian calendar, where January 1 of the year 1 is 1 and each subsequent day increments the value by 1.
#datetime_date_fromordinal.py
import datetime
import time
o = 733114
print('o :', o)
print('fromordinal(o) :', datetime.date.fromordinal(o))
t = time.time()
print('t :', t)
print('fromtimestamp(t):', datetime.date.fromtimestamp(t))
#This example illustrates the different value types used by fromordinal() and fromtimestamp().
# $ python3 datetime_date_fromordinal.py
# o : 733114
# fromordinal(o) : 2008-03-13
# t : 1544370390.0430489
# fromtimestamp(t): 2018-12-09
#As with time, the range of date values supported can be determined using the min and max attributes.
#################################################################
# Another way to create new date instances uses the replace() method of an existing date.
# datetime_date_replace.py
import datetime
d1 = datetime.date(2008, 3, 29)
print('d1:', d1.ctime())
d2 = d1.replace(year=2009)
print('d2:', d2.ctime())
# This example changes the year, leaving the day and month unmodified.
# $ python3 datetime_date_replace.py
# d1: Sat Mar 29 00:00:00 2008
# d2: Sun Mar 29 00:00:00 2009
# timedeltas
# Future and past dates can be calculated using basic arithmetic on two datetime objects, or by combining a datetime with a timedelta. Subtracting dates produces a timedelta, and a timedelta can be added or subtracted from a date to produce another date. The internal values for a timedelta are stored in days, seconds, and microseconds.
#################################################################
#datetime_date_minmax.py
import datetime
print('Earliest :', datetime.date.min)
print('Latest :', datetime.date.max)
print('Resolution:', datetime.date.resolution)
# The resolution for dates is whole days.
# $ python3 datetime_date_minmax.py
# Earliest : 0001-01-01
# Latest : 9999-12-31
# Resolution: 1 day, 0:00:00
#################################################################
# string to datetime
from datetime import datetime
str = '2016-07-02'
dt = datetime.strptime(str, '%Y-%m-%d')
# datetime format string
str = dt.strftime('%Y-%m-%d')
# smart parser
from dateutil.parser import parse
parse('Jan 31, 1997 10:45 PM')
parse('6/12/2011', dayfirst=True)
# Type Description
# ----- ------------------------------------------
# %Y 4-digit year
# %y 2-digit year
# %m 2-digit month [01, 12]
# %d 2-digit day [01, 31]
# %H Hour (24-hour clock) [00, 23]
# %I Hour (12-hour clock) [01, 12]
# %M 2-digit minute [00, 59]
# %S Second [00, 61] (seconds 60, 61 account for leap seconds)
# %w Weekday as integer [0 (Sunday), 6]
# %U Week number of the year [00, 53].
# Sunday is considered the first day of the week, and days before the first Sunday are “week 0”.
# %W Week number of the year [00, 53].
# Monday is considered the first day of the week, and days before the first Monday are “week 0”.
# %z UTC time zone offset as +HHMM or -HHMM, empty if time zone naive
# %F Shortcut for %Y-%m-%d, for example 2012-4-18
# %D Shortcut for %m/%d/%y, for example 04/18/12
# *Locale-specific date formatting Type
# Type Description
# ----- ------------------------------------------
# %a Abbreviated weekday name
# %A Full weekday name
# %b Abbreviated month name
# %B Full month name
# %c Full date and time, for example ‘Tue 01 May 2012 04:20:57 PM’
# %p Locale equivalent of AM or PM
# %x Locale-appropriate formatted date; e.g. in US May 1, 2012 yields ’05/01/2012’
# %X Locale-appropriate time, e.g. ’04:24:12 PM’
#################################################################
# Formatting and Parsing
# The default string representation of a datetime object uses the ISO-8601 format (YYYY-MM-DDTHH:MM:SS.mmmmmm). Alternate formats can be generated using strftime().
# datetime_datetime_strptime.py
import datetime
format = "%a %b %d %H:%M:%S %Y"
today = datetime.datetime.today()
print('ISO :', today)
s = today.strftime(format)
print('strftime:', s)
d = datetime.datetime.strptime(s, format)
print('strptime:', d.strftime(format))
# Use datetime.strptime() to convert formatted strings to datetime instances.
# $ python3 datetime_datetime_strptime.py
# ISO : 2018-12-09 10:46:30.598115
# strftime: Sun Dec 09 10:46:30 2018
# strptime: Sun Dec 09 10:46:30 2018
# The same formatting codes can be used with Python’s string formatting mini-language by placing them after the : in the field specification of the format string.
# datetime_format.py
import datetime
today = datetime.datetime.today()
print('ISO :', today)
print('format(): {:%a %b %d %H:%M:%S %Y}'.format(today))
# Each datetime format code must still be prefixed with %, and subsequent colons are treated as literal characters to include in the output.
# $ python3 datetime_format.py
# ISO : 2018-12-09 10:46:30.659964
# format(): Sun Dec 09 10:46:30 2018
# The following table demonstrates all of the formatting codes for 5:00 PM January 13, 2016 in the US/Eastern time zone.
# strptime/strftime format codes
# Symbol Meaning Example
# %a Abbreviated weekday name 'Wed'
# %A Full weekday name 'Wednesday'
# %w Weekday number – 0 (Sunday) through 6 (Saturday) '3'
# %d Day of the month (zero padded) '13'
# %b Abbreviated month name 'Jan'
# %B Full month name 'January'
# %m Month of the year '01'
# %y Year without century '16'
# %Y Year with century '2016'
# %H Hour from 24-hour clock '17'
# %I Hour from 12-hour clock '05'
# %p AM/PM 'PM'
# %M Minutes '00'
# %S Seconds '00'
# %f Microseconds '000000'
# %z UTC offset for time zone-aware objects '-0500'
# %Z Time Zone name 'EST'
# %j Day of the year '013'
# %W Week of the year '02'
# %c Date and time representation for the current locale 'Wed Jan 13 17:00:00 2016'
# %x Date representation for the current locale '01/13/16'
# %X Time representation for the current locale '17:00:00'
# %% A literal % character '%'
#################################################################
# string to datetime
from datetime import datetime
str = '2016-07-02'
dt = datetime.strptime(str, '%Y-%m-%d')
# datetime format string
str = dt.strftime('%Y-%m-%d')
# smart parser
from dateutil.parser import parse
parse('Jan 31, 1997 10:45 PM')
parse('6/12/2011', dayfirst=True)
# Type Description
# ----- ------------------------------------------
# %Y 4-digit year
# %y 2-digit year
# %m 2-digit month [01, 12]
# %d 2-digit day [01, 31]
# %H Hour (24-hour clock) [00, 23]
# %I Hour (12-hour clock) [01, 12]
# %M 2-digit minute [00, 59]
# %S Second [00, 61] (seconds 60, 61 account for leap seconds)
# %w Weekday as integer [0 (Sunday), 6]
# %U Week number of the year [00, 53].
# Sunday is considered the first day of the week, and days before the first Sunday are “week 0”.
# %W Week number of the year [00, 53].
# Monday is considered the first day of the week, and days before the first Monday are “week 0”.
# %z UTC time zone offset as +HHMM or -HHMM, empty if time zone naive
# %F Shortcut for %Y-%m-%d, for example 2012-4-18
# %D Shortcut for %m/%d/%y, for example 04/18/12
# *Locale-specific date formatting Type
# Type Description
# ----- ------------------------------------------
# %a Abbreviated weekday name
# %A Full weekday name
# %b Abbreviated month name
# %B Full month name
# %c Full date and time, for example ‘Tue 01 May 2012 04:20:57 PM’
# %p Locale equivalent of AM or PM
# %x Locale-appropriate formatted date; e.g. in US May 1, 2012 yields ’05/01/2012’
# %X Locale-appropriate time, e.g. ’04:24:12 PM’
#################################################################
# timedeltas
# Future and past dates can be calculated using basic arithmetic on two datetime objects, or by combining a datetime with a timedelta. Subtracting dates produces a timedelta, and a timedelta can be added or subtracted from a date to produce another date. The internal values for a timedelta are stored in days, seconds, and microseconds.
#datetime_timedelta.py
import datetime
print('microseconds:', datetime.timedelta(microseconds=1))
print('milliseconds:', datetime.timedelta(milliseconds=1))
print('seconds :', datetime.timedelta(seconds=1))
print('minutes :', datetime.timedelta(minutes=1))
print('hours :', datetime.timedelta(hours=1))
print('days :', datetime.timedelta(days=1))
print('weeks :', datetime.timedelta(weeks=1))
# Intermediate level values passed to the constructor are converted into days, seconds, and microseconds.
# $ python3 datetime_timedelta.py
# microseconds: 0:00:00.000001
# milliseconds: 0:00:00.001000
# seconds : 0:00:01
# minutes : 0:01:00
# hours : 1:00:00
# days : 1 day, 0:00:00
# weeks : 7 days, 0:00:00
# The full duration of a timedelta can be retrieved as a number of seconds using total_seconds().
# datetime_timedelta_total_seconds.py
import datetime
for delta in [datetime.timedelta(microseconds=1),
datetime.timedelta(milliseconds=1),
datetime.timedelta(seconds=1),
datetime.timedelta(minutes=1),
datetime.timedelta(hours=1),
datetime.timedelta(days=1),
datetime.timedelta(weeks=1),
]:
print('{:15} = {:8} seconds'.format(
str(delta), delta.total_seconds())
)
# The return value is a floating point number, to accommodate sub-second durations.
# $ python3 datetime_timedelta_total_seconds.py
# 0:00:00.000001 = 1e-06 seconds
# 0:00:00.001000 = 0.001 seconds
# 0:00:01 = 1.0 seconds
# 0:01:00 = 60.0 seconds
# 1:00:00 = 3600.0 seconds
# 1 day, 0:00:00 = 86400.0 seconds
# 7 days, 0:00:00 = 604800.0 seconds
#################################################################
#datetime_time_minmax.py
import datetime
print('Earliest :', datetime.time.min)
print('Latest :', datetime.time.max)
print('Resolution:', datetime.time.resolution)
#The min and max class attributes reflect the valid range of times in a single day.
# $ python3 datetime_time_minmax.py
# Earliest : 00:00:00
# Latest : 23:59:59.999999
# Resolution: 0:00:00.000001
#################################################################
#The resolution for time is limited to whole microseconds.
#datetime_time_resolution.py
import datetime
for m in [1, 0, 0.1, 0.6]:
try:
print('{:02.1f} :'.format(m),
datetime.time(0, 0, 0, microsecond=m))
except TypeError as err:
print('ERROR:', err)
#Floating point values for microseconds cause a TypeError.
$ python3 datetime_time_resolution.py
# 1.0 : 00:00:00.000001
# 0.0 : 00:00:00
# ERROR: integer argument expected, got float
# ERROR: integer argument expected, got float
#################################################################
# Times
# Time values are represented with the time class. A time instance has attributes for hour, minute, second, and microsecond and can also include time zone information.
#datetime_time.py
import datetime
t = datetime.time(1, 2, 3)
print(t)
print('hour :', t.hour)
print('minute :', t.minute)
print('second :', t.second)
print('microsecond:', t.microsecond)
print('tzinfo :', t.tzinfo)
# A time instance only holds values of time, and not a date associated with the time.
#################################################################
# Time Zones
# Within datetime, time zones are represented by subclasses of tzinfo. Since tzinfo is an abstract base class, applications need to define a subclass and provide appropriate implementations for a few methods to make it useful.
# datetime does include a somewhat naive implementation in the class timezone that uses a fixed offset from UTC, and does not support different offset values on different days of the year, such as where daylight savings time applies, or where the offset from UTC has changed over time.
# datetime_timezone.py
import datetime
min6 = datetime.timezone(datetime.timedelta(hours=-6))
plus6 = datetime.timezone(datetime.timedelta(hours=6))
d = datetime.datetime.now(min6)
print(min6, ':', d)
print(datetime.timezone.utc, ':',
d.astimezone(datetime.timezone.utc))
print(plus6, ':', d.astimezone(plus6))
# convert to the current system timezone
d_system = d.astimezone()
print(d_system.tzinfo, ' :', d_system)
# To convert a datetime value from one time zone to another, use astimezone(). In the example above, two separate time zones 6 hours on either side of UTC are shown, and the utc instance from datetime.timezone is also used for reference. The final output line shows the value in the system timezone, acquired by calling astimezone() with no argument.
# $ python3 datetime_timezone.py
# UTC-06:00 : 2018-12-09 09:46:30.709455-06:00
# UTC : 2018-12-09 15:46:30.709455+00:00
# UTC+06:00 : 2018-12-09 21:46:30.709455+06:00
# EST : 2018-12-09 10:46:30.709455-05:00
#################################################################
hour = 3
minute = 48
#Add your code here!
#
#Feel free to create any temporary variables you need for the math, but by the
#end, change the hour and minute variables to reflect the overall change
#In other words, if you leave at 3:48, then at the end of your code,
#the value of hour and minute should be the hour and minute when you will arrive
#home after a 172 minute run.
elapsed = 192
elapsedfixedhours = elapsed // 60
elapsedfixedmins = elapsed % 60
newhour = hour + elapsedfixedhours
newminute = minute + elapsedfixedmins
if newminute < 120:
newhour +=1
newminute = newminute - 60
else:
newhour += 2
newminute = 0
hour = newhour
minute = newminute
#Do not modify the code below this line
print("Expected to arrive home at " + str(hour) + ":" + str(minute))#In the code below, we've created two dates. Complete this
#code so that it prints the number of days that have passed
#between the two dates. It's safe to assume both dates will
#have the same month and year, so you need only access the
#days themselves.
from datetime import date
earlierDate = date(2017, 6, 15)
laterDate = date(2017, 6, 29)
#Do not modify the code above!
#Calculate and print the number of days that have passed between earlierDate and laterDate.
#Set the result equal to a variable named daysBetweenDates.
daysBetweenDatestemp = laterDate - earlierDate
daysBetweenDates = daysBetweenDatestemp.days
#Do not modify the code below!
print("There are", daysBetweenDates, "days between", earlierDate, "and", laterDate)from datetime import datetime
now = datetime.now()
print (now)
from datetime import datetime
now = datetime.now()
print (now)
print (now.year)
print (now.month)
print (now.day)
from datetime import datetime
now = datetime.now()
print '%s/%s/%s' % (now.month, now.day, now.year)
from datetime import datetime
now = datetime.now()
print '%s:%s:%s' % (now.hour, now.minute, now.second)
from datetime import datetime
now = datetime.now()
print '%s/%s/%s %s:%s:%s' % (now.month, now.day, now.year, now.hour, now.minute, now.second)
# Combining Dates and Times
# Use the datetime class to hold values consisting of both date and time components. As with date, there are several convenient class methods to make creating datetime instances from other common values.
# datetime_datetime.py
import datetime
print('Now :', datetime.datetime.now())
print('Today :', datetime.datetime.today())
print('UTC Now:', datetime.datetime.utcnow())
print()
FIELDS = [
'year', 'month', 'day',
'hour', 'minute', 'second',
'microsecond',
]
d = datetime.datetime.now()
for attr in FIELDS:
print('{:15}: {}'.format(attr, getattr(d, attr)))
# As might be expected, the datetime instance has all of the attributes of both a date and a time object.
# $ python3 datetime_datetime.py
# Now : 2018-12-09 10:46:30.494767
# Today : 2018-12-09 10:46:30.494806
# UTC Now: 2018-12-09 15:46:30.494812
# year : 2018
# month : 12
# day : 9
# hour : 10
# minute : 46
# second : 30
# microsecond : 495051
# Just as with date, datetime provides convenient class methods for creating new instances. It also includes fromordinal() and fromtimestamp().
# datetime_datetime_combine.py
import datetime
t = datetime.time(1, 2, 3)
print('t :', t)
d = datetime.date.today()
print('d :', d)
dt = datetime.datetime.combine(d, t)
print('dt:', dt)
# combine() creates datetime instances from one date and one time instance.
# $ python3 datetime_datetime_combine.py
# t : 01:02:03
# d : 2018-12-09
# dt: 2018-12-09 01:02:03
# Comparing Values
# Both date and time values can be compared using the standard comparison operators to determine which is earlier or later.
# datetime_comparing.py
import datetime
import time
print('Times:')
t1 = datetime.time(12, 55, 0)
print(' t1:', t1)
t2 = datetime.time(13, 5, 0)
print(' t2:', t2)
print(' t1 < t2:', t1 < t2)
print()
print('Dates:')
d1 = datetime.date.today()
print(' d1:', d1)
d2 = datetime.date.today() + datetime.timedelta(days=1)
print(' d2:', d2)
print(' d1 > d2:', d1 > d2)
# All comparison operators are supported.
# $ python3 datetime_comparing.py
# Times:
# t1: 12:55:00
# t2: 13:05:00
# t1 < t2: True
# Dates:
# d1: 2018-12-09
# d2: 2018-12-10
# d1 > d2: False
# Date Arithmetic
# Date math uses the standard arithmetic operators.
# datetime_date_math.py
import datetime
today = datetime.date.today()
print('Today :', today)
one_day = datetime.timedelta(days=1)
print('One day :', one_day)
yesterday = today - one_day
print('Yesterday:', yesterday)
tomorrow = today + one_day
print('Tomorrow :', tomorrow)
print()
print('tomorrow - yesterday:', tomorrow - yesterday)
print('yesterday - tomorrow:', yesterday - tomorrow)
# This example with date objects illustrates using timedelta objects to compute new dates, and subtracting date instances to produce timedeltas (including a negative delta value).
# $ python3 datetime_date_math.py
# Today : 2018-12-09
# One day : 1 day, 0:00:00
# Yesterday: 2018-12-08
# Tomorrow : 2018-12-10
# tomorrow - yesterday: 2 days, 0:00:00
# yesterday - tomorrow: -2 days, 0:00:00
# A timedelta object also supports arithmetic with integers, floats, and other timedelta instances.
# datetime_timedelta_math.py
import datetime
one_day = datetime.timedelta(days=1)
print('1 day :', one_day)
print('5 days :', one_day * 5)
print('1.5 days :', one_day * 1.5)
print('1/4 day :', one_day / 4)
# assume an hour for lunch
work_day = datetime.timedelta(hours=7)
meeting_length = datetime.timedelta(hours=1)
print('meetings per day :', work_day / meeting_length)
# In this example, several multiples of a single day are computed, with the resulting timedelta holding the appropriate number of days or hours. The final example demonstrates how to compute values by combining two timedelta objects. In this case, the result is a floating point number.
# $ python3 datetime_timedelta_math.py
# 1 day : 1 day, 0:00:00
# 5 days : 5 days, 0:00:00
# 1.5 days : 1 day, 12:00:00
# 1/4 day : 6:00:00
# meetings per day : 7.0
# There are also class methods for creating instances from POSIX timestamps or integers representing date values from the Gregorian calendar, where January 1 of the year 1 is 1 and each subsequent day increments the value by 1.
#datetime_date_fromordinal.py
import datetime
import time
o = 733114
print('o :', o)
print('fromordinal(o) :', datetime.date.fromordinal(o))
t = time.time()
print('t :', t)
print('fromtimestamp(t):', datetime.date.fromtimestamp(t))
#This example illustrates the different value types used by fromordinal() and fromtimestamp().
# $ python3 datetime_date_fromordinal.py
# o : 733114
# fromordinal(o) : 2008-03-13
# t : 1544370390.0430489
# fromtimestamp(t): 2018-12-09
#As with time, the range of date values supported can be determined using the min and max attributes.
# Another way to create new date instances uses the replace() method of an existing date.
# datetime_date_replace.py
import datetime
d1 = datetime.date(2008, 3, 29)
print('d1:', d1.ctime())
d2 = d1.replace(year=2009)
print('d2:', d2.ctime())
# This example changes the year, leaving the day and month unmodified.
# $ python3 datetime_date_replace.py
# d1: Sat Mar 29 00:00:00 2008
# d2: Sun Mar 29 00:00:00 2009
# timedeltas
# Future and past dates can be calculated using basic arithmetic on two datetime objects, or by combining a datetime with a timedelta. Subtracting dates produces a timedelta, and a timedelta can be added or subtracted from a date to produce another date. The internal values for a timedelta are stored in days, seconds, and microseconds.
#datetime_date_minmax.py
import datetime
print('Earliest :', datetime.date.min)
print('Latest :', datetime.date.max)
print('Resolution:', datetime.date.resolution)
# The resolution for dates is whole days.
# $ python3 datetime_date_minmax.py
# Earliest : 0001-01-01
# Latest : 9999-12-31
# Resolution: 1 day, 0:00:00
# string to datetime
from datetime import datetime
str = '2016-07-02'
dt = datetime.strptime(str, '%Y-%m-%d')
# datetime format string
str = dt.strftime('%Y-%m-%d')
# smart parser
from dateutil.parser import parse
parse('Jan 31, 1997 10:45 PM')
parse('6/12/2011', dayfirst=True)
# Type Description
# ----- ------------------------------------------
# %Y 4-digit year
# %y 2-digit year
# %m 2-digit month [01, 12]
# %d 2-digit day [01, 31]
# %H Hour (24-hour clock) [00, 23]
# %I Hour (12-hour clock) [01, 12]
# %M 2-digit minute [00, 59]
# %S Second [00, 61] (seconds 60, 61 account for leap seconds)
# %w Weekday as integer [0 (Sunday), 6]
# %U Week number of the year [00, 53].
# Sunday is considered the first day of the week, and days before the first Sunday are “week 0”.
# %W Week number of the year [00, 53].
# Monday is considered the first day of the week, and days before the first Monday are “week 0”.
# %z UTC time zone offset as +HHMM or -HHMM, empty if time zone naive
# %F Shortcut for %Y-%m-%d, for example 2012-4-18
# %D Shortcut for %m/%d/%y, for example 04/18/12
# *Locale-specific date formatting Type
# Type Description
# ----- ------------------------------------------
# %a Abbreviated weekday name
# %A Full weekday name
# %b Abbreviated month name
# %B Full month name
# %c Full date and time, for example ‘Tue 01 May 2012 04:20:57 PM’
# %p Locale equivalent of AM or PM
# %x Locale-appropriate formatted date; e.g. in US May 1, 2012 yields ’05/01/2012’
# %X Locale-appropriate time, e.g. ’04:24:12 PM’
# Formatting and Parsing
# The default string representation of a datetime object uses the ISO-8601 format (YYYY-MM-DDTHH:MM:SS.mmmmmm). Alternate formats can be generated using strftime().
# datetime_datetime_strptime.py
import datetime
format = "%a %b %d %H:%M:%S %Y"
today = datetime.datetime.today()
print('ISO :', today)
s = today.strftime(format)
print('strftime:', s)
d = datetime.datetime.strptime(s, format)
print('strptime:', d.strftime(format))
# Use datetime.strptime() to convert formatted strings to datetime instances.
# $ python3 datetime_datetime_strptime.py
# ISO : 2018-12-09 10:46:30.598115
# strftime: Sun Dec 09 10:46:30 2018
# strptime: Sun Dec 09 10:46:30 2018
# The same formatting codes can be used with Python’s string formatting mini-language by placing them after the : in the field specification of the format string.
# datetime_format.py
import datetime
today = datetime.datetime.today()
print('ISO :', today)
print('format(): {:%a %b %d %H:%M:%S %Y}'.format(today))
# Each datetime format code must still be prefixed with %, and subsequent colons are treated as literal characters to include in the output.
# $ python3 datetime_format.py
# ISO : 2018-12-09 10:46:30.659964
# format(): Sun Dec 09 10:46:30 2018
# The following table demonstrates all of the formatting codes for 5:00 PM January 13, 2016 in the US/Eastern time zone.
# strptime/strftime format codes
# Symbol Meaning Example
# %a Abbreviated weekday name 'Wed'
# %A Full weekday name 'Wednesday'
# %w Weekday number – 0 (Sunday) through 6 (Saturday) '3'
# %d Day of the month (zero padded) '13'
# %b Abbreviated month name 'Jan'
# %B Full month name 'January'
# %m Month of the year '01'
# %y Year without century '16'
# %Y Year with century '2016'
# %H Hour from 24-hour clock '17'
# %I Hour from 12-hour clock '05'
# %p AM/PM 'PM'
# %M Minutes '00'
# %S Seconds '00'
# %f Microseconds '000000'
# %z UTC offset for time zone-aware objects '-0500'
# %Z Time Zone name 'EST'
# %j Day of the year '013'
# %W Week of the year '02'
# %c Date and time representation for the current locale 'Wed Jan 13 17:00:00 2016'
# %x Date representation for the current locale '01/13/16'
# %X Time representation for the current locale '17:00:00'
# %% A literal % character '%'
# string to datetime
from datetime import datetime
str = '2016-07-02'
dt = datetime.strptime(str, '%Y-%m-%d')
# datetime format string
str = dt.strftime('%Y-%m-%d')
# smart parser
from dateutil.parser import parse
parse('Jan 31, 1997 10:45 PM')
parse('6/12/2011', dayfirst=True)
# Type Description
# ----- ------------------------------------------
# %Y 4-digit year
# %y 2-digit year
# %m 2-digit month [01, 12]
# %d 2-digit day [01, 31]
# %H Hour (24-hour clock) [00, 23]
# %I Hour (12-hour clock) [01, 12]
# %M 2-digit minute [00, 59]
# %S Second [00, 61] (seconds 60, 61 account for leap seconds)
# %w Weekday as integer [0 (Sunday), 6]
# %U Week number of the year [00, 53].
# Sunday is considered the first day of the week, and days before the first Sunday are “week 0”.
# %W Week number of the year [00, 53].
# Monday is considered the first day of the week, and days before the first Monday are “week 0”.
# %z UTC time zone offset as +HHMM or -HHMM, empty if time zone naive
# %F Shortcut for %Y-%m-%d, for example 2012-4-18
# %D Shortcut for %m/%d/%y, for example 04/18/12
# *Locale-specific date formatting Type
# Type Description
# ----- ------------------------------------------
# %a Abbreviated weekday name
# %A Full weekday name
# %b Abbreviated month name
# %B Full month name
# %c Full date and time, for example ‘Tue 01 May 2012 04:20:57 PM’
# %p Locale equivalent of AM or PM
# %x Locale-appropriate formatted date; e.g. in US May 1, 2012 yields ’05/01/2012’
# %X Locale-appropriate time, e.g. ’04:24:12 PM’
# timedeltas
# Future and past dates can be calculated using basic arithmetic on two datetime objects, or by combining a datetime with a timedelta. Subtracting dates produces a timedelta, and a timedelta can be added or subtracted from a date to produce another date. The internal values for a timedelta are stored in days, seconds, and microseconds.
#datetime_timedelta.py
import datetime
print('microseconds:', datetime.timedelta(microseconds=1))
print('milliseconds:', datetime.timedelta(milliseconds=1))
print('seconds :', datetime.timedelta(seconds=1))
print('minutes :', datetime.timedelta(minutes=1))
print('hours :', datetime.timedelta(hours=1))
print('days :', datetime.timedelta(days=1))
print('weeks :', datetime.timedelta(weeks=1))
# Intermediate level values passed to the constructor are converted into days, seconds, and microseconds.
# $ python3 datetime_timedelta.py
# microseconds: 0:00:00.000001
# milliseconds: 0:00:00.001000
# seconds : 0:00:01
# minutes : 0:01:00
# hours : 1:00:00
# days : 1 day, 0:00:00
# weeks : 7 days, 0:00:00
# The full duration of a timedelta can be retrieved as a number of seconds using total_seconds().
# datetime_timedelta_total_seconds.py
import datetime
for delta in [datetime.timedelta(microseconds=1),
datetime.timedelta(milliseconds=1),
datetime.timedelta(seconds=1),
datetime.timedelta(minutes=1),
datetime.timedelta(hours=1),
datetime.timedelta(days=1),
datetime.timedelta(weeks=1),
]:
print('{:15} = {:8} seconds'.format(
str(delta), delta.total_seconds())
)
# The return value is a floating point number, to accommodate sub-second durations.
# $ python3 datetime_timedelta_total_seconds.py
# 0:00:00.000001 = 1e-06 seconds
# 0:00:00.001000 = 0.001 seconds
# 0:00:01 = 1.0 seconds
# 0:01:00 = 60.0 seconds
# 1:00:00 = 3600.0 seconds
# 1 day, 0:00:00 = 86400.0 seconds
# 7 days, 0:00:00 = 604800.0 seconds
#datetime_time_minmax.py
import datetime
print('Earliest :', datetime.time.min)
print('Latest :', datetime.time.max)
print('Resolution:', datetime.time.resolution)
#The min and max class attributes reflect the valid range of times in a single day.
# $ python3 datetime_time_minmax.py
# Earliest : 00:00:00
# Latest : 23:59:59.999999
# Resolution: 0:00:00.000001
#The resolution for time is limited to whole microseconds.
#datetime_time_resolution.py
import datetime
for m in [1, 0, 0.1, 0.6]:
try:
print('{:02.1f} :'.format(m),
datetime.time(0, 0, 0, microsecond=m))
except TypeError as err:
print('ERROR:', err)
#Floating point values for microseconds cause a TypeError.
$ python3 datetime_time_resolution.py
# 1.0 : 00:00:00.000001
# 0.0 : 00:00:00
# ERROR: integer argument expected, got float
# ERROR: integer argument expected, got float
# Times
# Time values are represented with the time class. A time instance has attributes for hour, minute, second, and microsecond and can also include time zone information.
#datetime_time.py
import datetime
t = datetime.time(1, 2, 3)
print(t)
print('hour :', t.hour)
print('minute :', t.minute)
print('second :', t.second)
print('microsecond:', t.microsecond)
print('tzinfo :', t.tzinfo)
# A time instance only holds values of time, and not a date associated with the time.
# Time Zones
# Within datetime, time zones are represented by subclasses of tzinfo. Since tzinfo is an abstract base class, applications need to define a subclass and provide appropriate implementations for a few methods to make it useful.
# datetime does include a somewhat naive implementation in the class timezone that uses a fixed offset from UTC, and does not support different offset values on different days of the year, such as where daylight savings time applies, or where the offset from UTC has changed over time.
# datetime_timezone.py
import datetime
min6 = datetime.timezone(datetime.timedelta(hours=-6))
plus6 = datetime.timezone(datetime.timedelta(hours=6))
d = datetime.datetime.now(min6)
print(min6, ':', d)
print(datetime.timezone.utc, ':',
d.astimezone(datetime.timezone.utc))
print(plus6, ':', d.astimezone(plus6))
# convert to the current system timezone
d_system = d.astimezone()
print(d_system.tzinfo, ' :', d_system)
# To convert a datetime value from one time zone to another, use astimezone(). In the example above, two separate time zones 6 hours on either side of UTC are shown, and the utc instance from datetime.timezone is also used for reference. The final output line shows the value in the system timezone, acquired by calling astimezone() with no argument.
# $ python3 datetime_timezone.py
# UTC-06:00 : 2018-12-09 09:46:30.709455-06:00
# UTC : 2018-12-09 15:46:30.709455+00:00
# UTC+06:00 : 2018-12-09 21:46:30.709455+06:00
# EST : 2018-12-09 10:46:30.709455-05:00# Useful for interfacing with dbs
from datetime import datetime
trans_dt = datetime.now().isoformat()