Python time module
In Python documents, time is classified in Generic Operating System Services. In other words, the functions it provides are closer to the operating system level. Reading through the document, we can see that the time module is carried out around Unix Timestamp.
Get current time and conversion time format
// time() returns the time in timestamp format (offset in seconds relative to 1.1 00:00:00) >>> time.time() 1632643244.288437
// ctime() returns the time in string form. You can pass in the time stamp format for conversion >>> time.ctime() 'Sun Sep 26 16:02:23 2021' >>> time.ctime(time.time()) 'Sun Sep 26 16:03:13 2021'
struct_time has 9 elements in total, of which the first 6 are year, month, day, hour, minute and second, and the last three respectively represent:
☆ tm_wday the day of the week (Sunday is 0)
☆ tm_ What day of the year is yday
☆ tm_ Is isdst daylight saving time
// Astime () returns the time in the form of string, which can be passed into struct_time is the form of time, which is used for conversion >>> time.asctime() 'Sun Sep 26 16:03:35 2021' >>> time.asctime(time.localtime()) 'Sun Sep 26 16:03:52 2021'
// localtime() returns the struct of the current time_ Time format, which can be passed in timestamp format for conversion >>> time.localtime() time.struct_time(tm_year=2021, tm_mon=9, tm_mday=26, tm_hour=16, tm_min=4, tm_sec=16, tm_wday=6, tm_yday=269, tm_isdst=0) >>> time.localtime(time.time()) time.struct_time(tm_year=2021, tm_mon=9, tm_mday=26, tm_hour=16, tm_min=5, tm_sec=1, tm_wday=6, tm_yday=269, tm_isdst=0)
// gmtime() returns the struct of the current time_ Time form, UTC time zone (0 time zone), can be passed in timestamp format time for conversion >>> time.gmtime() time.struct_time(tm_year=2021, tm_mon=9, tm_mday=26, tm_hour=8, tm_min=5, tm_sec=26, tm_wday=6, tm_yday=269, tm_isdst=0) >>> time.gmtime(time.time()) time.struct_time(tm_year=2021, tm_mon=9, tm_mday=26, tm_hour=8, tm_min=5, tm_sec=42, tm_wday=6, tm_yday=269, tm_isdst=0)
Time formatting
// time.mktime() takes a struct_ Convert time format to timestamp >>> time.mktime(time.localtime()) 1632644087.0
// time.strftime(format[,t]) puts a struct_time time is converted to a formatted time string. If t is not specified, time.localtime() is passed in
>>> time.strftime("%Y-%m-%d %H:%M:%S", time.localtime())
'2021-09-26 16:16:25'
| Symbol | explain |
|---|---|
| %c | Local corresponding date and time representation |
| %x | Local corresponding date |
| %X | Local corresponding time |
| %y | Remove the year of the century (00 – 99) |
| %Y | Full year |
| %m | Month (01 – 12) |
| %b | Local simplified month name |
| %B | Local full month name |
| %d | Day of the month (01 – 31) |
| %j | Day of the year (001 – 366) |
| %U | The number of weeks in a year. (00 – 53 Sunday is the beginning of the week.) |
| %W | It is basically the same as% U, except that% W starts on Monday. |
| %w | The day of the week (0 – 6, 0 is Sunday) |
| %a | Local simplified week name |
| %A | Local full week name |
| %H | The hour of the day (24 hours, 00 – 23) |
| %I | The first few hours (12 hour system, 01 – 12) |
| %p | The corresponding character of local am or pm, "% p" is effective only when used with "% I". |
| %M | Minutes (00 – 59) |
| %S | Seconds (01 – 61). The document emphasizes that it is really 0 – 61, not 59. Leap year seconds account for two seconds |
| %Z | The name of the time zone (if no empty character exists) |
| %% | '%' character |
t PI DAR
time.sleep(): the thread delays running for the specified time. The unit is seconds.
time.clock(): it should be noted that this has different meanings on different systems. On UNIX systems, it returns the "process time", which is a floating-point number (timestamp) in seconds. In WINDOWS, the first call returns the actual running time of the process. The second call is the running time from the first call to the present. (in fact, it is based on QueryPerformanceCounter() on WIN32, which is more accurate than the representation of milliseconds)
Other built-in functions of time module
altzone(): returns the offset seconds of the daylight saving time region in Western Greenwich. If the region is east of Greenwich, it will return a negative value (such as Western Europe, including the UK). Only the region enabled for daylight saving time can be used.
tzset(): reinitialize the time related settings according to the environment variable TZ.
Python datetime module
date class
// max: the maximum date that the date object can represent
>>> print('date.max:', date.max)
date.max: 9999-12-31
// min: the minimum date that the date object can represent
>>> print('date.min:', date.min)
date.min: 0001-01-01
// resolution: the date object represents the smallest unit of the date. This is heaven
>>> print('date.resolution:', date.resolution)
date.resolution: 1 day, 0:00:00
// today(): returns a date object representing the current local date
>>> print('date.today():', date.today())
date.today(): 2021-09-26
// From time stamp (timestamp): returns a date object according to a given time stamp
>>> print('date.fromtimestamp():', date.fromtimestamp(time.time()))
date.fromtimestamp(): 2021-09-26
Instance methods and properties provided by date:
| attribute | explain |
|---|---|
| .year | Return year |
| .month | Return month |
| .day | Return day |
| .replace(year, month, day) | Generate a new date object, and replace the attributes in the original object with the year, month and day specified by the parameter. (the original object remains unchanged) |
| .weekday() | Return weekday. If it is Monday, return 0; If it is Tuesday, return 1, and so on |
| .isoweekday() | Return weekday. If it is Monday, return 1; If it is Tuesday, return 2, and so on |
| .isocalendar() | Return format, such as (year, wk num, wk day) |
| .isoformat() | Returns a string in the format of 'YYYY-MM-DD' |
| .strftime(fmt) | Custom format string. Similar to strftime in the time module. |
| .toordinal() | Return the Gregorian Calendar date corresponding to the date |
Example:
from datetime import date
today = date.today()
print('today:', today)
print('.year:', today.year)
print('.month:', today.month)
print('.replace():', today.replace(year=2017))
print('.weekday():', today.weekday())
print('.isoweekday():', today.isoweekday())
print('.isocalendar():', today.isocalendar())
print('.isoformat():', today.isoformat())
print('.strftime():', today.strftime('%Y-%m-%d'))
print('.toordinal():', today.toordinal())
result:
today: 2021-09-26 .year: 2021 .month: 9 .replace(): 2017-09-26 .weekday(): 6 .isoweekday(): 7 .isocalendar(): (2021, 38, 7) .isoformat(): 2021-09-26 .strftime(): 2021-09-26 .toordinal(): 738059
Date also overloads some operations, which allows us to perform the following operations on the date:
date2 = date1 + timedelta # date plus an interval to return a new date object
date2 = date1 – timedelta # date minus an interval to return a new date object
timedelta = date1 – date2 # two dates are subtracted to return a time interval object
Date1 < date2 # two dates are compared
time class
Class properties defined by time class:
min,max: time Class can represent the minimum and maximum time. Among them, time.min = time(0, 0, 0, 0)， time.max = time(23, 59, 59, 999999) resolution: The smallest unit of time, here is 1 microsecond time Class provides instance methods and properties: .hour,.minute,.second,.microsecond: Hour, minute, second, microsecond .tzinfo: Time zone information .replace([hour[, minute[, second[, microsecond[, tzinfo]]]]]): Create a new time object and replace the attributes in the original object with the hours, minutes, seconds and microseconds specified by the parameters (the original object remains unchanged); .isoformat(): Return type, such as " HH:MM:SS"String representation of format; .strftime(fmt): Returns a custom format string.
Like date, you can also compare two time objects or subtract to return a time interval object. No examples are provided here.
datetime class
datetime is a combination of date and time, including all information of date and time.
Class properties and methods defined by datetime class:
| attribute | explain |
|---|---|
| min | The minimum value that datetime can represent |
| max | The maximum value that datetime can represent |
| resolution | datetime minimum unit |
| today() | Returns a datetime object representing the current local time |
| now([tz]) | Returns a datetime object representing the current local time. If the parameter tz is provided, the local time of the time zone indicated by the tz parameter is obtained |
| utcnow() | Returns a datetime object of the current utc time |
| fromtimestamp(timestamp[, tz]) | Create a datetime object according to the time. The parameter tz specifies the time zone information |
| utcfromtimestamp(timestamp) | Create a datetime object based on time |
| combine(date, time) | Create a datetime object based on date and time |
| strptime(date_string, format) | Converts a format string to a datetime object |
Example:
from datetime import datetime
import time
print('datetime.max:', datetime.max)
print('datetime.min:', datetime.min)
print('datetime.resolution:', datetime.resolution)
print('today():', datetime.today())
print('now():', datetime.now())
print('utcnow():', datetime.utcnow())
print('fromtimestamp(tmstmp):', datetime.fromtimestamp(time.time()))
print('utcfromtimestamp(tmstmp):', datetime.utcfromtimestamp(time.time()))
result:
datetime.max: 9999-12-31 23:59:59.999999 datetime.min: 0001-01-01 00:00:00 datetime.resolution: 0:00:00.000001 today(): 2021-09-26 17:51:10.105650 now(): 2021-09-26 17:51:10.105650 utcnow(): 2021-09-26 09:51:10.105650 fromtimestamp(tmstmp): 2021-09-26 17:51:10.106650 utcfromtimestamp(tmstmp): 2021-09-26 09:51:10.106650
timedelta class
The timedelta function returns a timedelta object, that is, an object representing a time interval.
import datetime >>> print(datetime.datetime.today() - datetime.timedelta(10)) 2021-09-16 18:01:34.757877