The datetime module is dedicated to time and date processing
The commonly used functions are as follows:
import datetime
print(datetime.datetime.now())
# datetime.today()
#2020- 09- 2123:13:05.245157 print(datetime.datetime.today())
#2020-09-2123:13:57.062886
print(datetime.datetime.strptime('2020/08/09',format('%Y/%m/%d')))
#2020- 08- 0900:00:00 print(datetime.datetime.strptime('20-08-09',format('%y-%m-%d')))
#2020-08-0900:00:00
Receive a time tuple, and return the local time expressed as a readable string, the format is determined by the parameter format.
dt = datetime.datetime.now()print("======================")print('time:(%Y-%m-%d %H:%M:%S %f): ',dt.strftime('%Y-%m-%d %H:%M:%S %f'))print('time:(%Y-%m-%d %H:%M:%S %p): ', dt.strftime('%y-%m-%d %I:%M:%S %p'))print('Abbreviation of the week%%a: %s '% dt.strftime('%a'))print('All week%%A: %s '% dt.strftime('%A'))print('Month abbreviation%%b: %s '% dt.strftime('%b'))print('Month batch%%B: %s '% dt.strftime('%B'))print('Date time%%c: %s '% dt.strftime('%c'))print('Today is the first of this week%s days'% dt.strftime('%w'))print('Today is the first of this year%s days'% dt.strftime('%j'))print('This week is the first of the year%s week'% dt.strftime('%U'))print('Today is the first of the month%s days'% dt.strftime('%d'))'''
====================== time:(%Y-%m-%d %H:%M:%S %f):2020-09-2123:30:51573645time:(%Y-%m-%d %H:%M:%S %p):20-09-2111:30:51 PM
Abbreviation of the week%a: Mon
All week%A: Monday
Month abbreviation%b: Sep
Month batch%B: September
Date time%c: Mon Sep 2123:30:512020
Today is the first day of the week
Today is the 265th day of this year
This week is the 38th week of the year
Today is the 21st day of the month
'''
When writing code, it often involves the mutual conversion of time, date, and time stamp.
# Import module
import time, datetime
# Character type time
testStr ='2020-09-21 23:26:33'
# Convert to time array
timeArray = time.strptime(testStr,"%Y-%m-%d %H:%M:%S")print(timeArray)
# timeArray can call tm_year etc.
print(timeArray.tm_year) # 2020
# Convert to timestamp
timeStamp =int(time.mktime(timeArray))print(timeStamp) # 1600701993
# The result is as follows
time.struct_time(tm_year=2020, tm_mon=9, tm_mday=21, tm_hour=23, tm_min=26, tm_sec=33, tm_wday=0, tm_yday=265, tm_isdst=-1)20201600701993
testStr1 ="2020-09-21 23:40:00"
# Convert to array
timeArray = time.strptime(testStr1,"%Y-%m-%d %H:%M:%S")
# Convert to other display format
otherStyleTime = time.strftime("%Y/%m/%d %H:%M:%S", timeArray)print(otherStyleTime)
tss3 ="2020/09/21 23:40:00"
timeArray = time.strptime(tss3,"%Y/%m/%d %H:%M:%S")
otherStyleTime = time.strftime("%Y-%m-%d %H:%M:%S", timeArray)print(otherStyleTime)"""
- - - - - - - - - - - - - - - - - - - - - - - 2020 /09/2123:40:002020-09-2123:40:00======================"""
# Use time
timeStamp =1600701993
timeArray = time.localtime(timeStamp)
otherStyleTime = time.strftime("%Y--%m--%d %H:%M:%S", timeArray)print(otherStyleTime) # 2020--09--2123:26:33
# Use datetime
timeStamp =1600101993
dateArray = datetime.datetime.fromtimestamp(timeStamp)
otherStyleTime = dateArray.strftime("%Y--%m--%d %H:%M:%S")print(otherStyleTime) # 2020--09--1500:46:33
# Use datetime, specify UTC time, the difference is 8 hours
timeStamp =1600201993
dateArray = datetime.datetime.utcfromtimestamp(timeStamp)
otherStyleTime = dateArray.strftime("%Y--%m--%d %H:%M:%S")print(otherStyleTime) # 2020--09--1520:33:13
print("+++++++++++++++++++++++++++++++++++++++++++")
# time to get the current timestamp
now =int(time.time()) # 1533952277
timeArray = time.localtime(now)print(timeArray)
otherStyleTime = time.strftime("%Y--%m--%d %H:%M:%S", timeArray)print(otherStyleTime)
# The result is as follows
"""
time.struct_time(tm_year=2020, tm_mon=9, tm_mday=21, tm_hour=23, tm_min=45, tm_sec=53, tm_wday=0, tm_yday=265, tm_isdst=0)2020--09--2123:45:53"""
# datetime to get the current time, array format
now = datetime.datetime.now()print(now)
otherStyleTime = now.strftime("%Y--%m--%d %H:%M:%S")print(otherStyleTime)
# The results are as follows:
"""
2020-09-2123:45:53.5434872020--09--2123:45:53"""
The string mentioned here is not a string in the general sense. It means that when reading data of date type, if the string has not been parsed in time, it is not a date type, then how should the string at this time be related to the timestamp? Convert between?
There are three commonly used forms of date and time:
import time; #Introduce the time module
ticks = time.time()print("The current timestamp is:", ticks)
The current timestamp is:1600704429.9781017
tm_struct = time.localtime(ticks)print(tm_struct)
time.struct_time(tm_year=2020, tm_mon=9, tm_mday=22, tm_hour=0, tm_min=8, tm_sec=2, tm_wday=1, tm_yday=266, tm_isdst=0)
Sometimes we need to get Greenwich Mean Time, then we can use the time.gmtime() function:
# Greenwich Mean Time
print(time.gmtime(ticks))
time.struct_time(tm_year=2020, tm_mon=9, tm_mday=21, tm_hour=16, tm_min=9, tm_sec=18, tm_wday=0, tm_yday=265, tm_isdst=0)
print(time.mktime(tm_struct))1600704621.0
There are many conversion methods, the simplest is asctime():
time_str = time.asctime( tm_struct )print(time_str)"""
Tue Sep 2200:12:142020"""
If you want to precisely control the format, we can use strftime():
tm_1=time.strftime("%Y-%m-%d %H:%M:%S", tm_struct)
tm_2=time.strftime("%a %b %d %H:%M:%S %Y", tm_struct)print(tm_1)print(tm_2)"""
2020-09-2200:14:13
Tue Sep 2200:14:132020"""
The function time.strptime() can complete this conversion, the following is an example
tm2_struct = time.strptime('2020-09-22 01:34:50',"%Y-%m-%d %H:%M:%S")print(tm2_struct)"""
time.struct_time(tm_year=2020, tm_mon=9, tm_mday=22, tm_hour=1, tm_min=34, tm_sec=50, tm_wday=1, tm_yday=266, tm_isdst=-1)"""
time.ctime() is similar to time.asctime(), please see the following example:
tm_3=time.ctime(ticks)print(tm_3)"""
Tue Sep 2200:17:542020"""
# If you want to precisely control the output string, I haven't found any existing functions. It is estimated that it can only be converted into a tuple first, and then formatted into a string.
# I wrote a conversion function:
def time2str(ticks, fmt='%a %b %d %H:%M:%S %Y'):
tm = time.localtime(ticks)return time.strftime(fmt, tm)
def str2time(str, fmt='%a %b %d %H:%M:%S %Y')：
tm = time.strptime(str, fmt)return time.mktime(tm)
# Here is also a reference function
Homework practice
pandas.to_datetime(arg, errors ='raise', utc = None, format = None, unit = None) convert a string to a date function
# Convert time string format, method two:
import pandas as pd
start = pd.to_datetime("20200922")print("===================================")print(start)
s=start.strftime('%Y-%m-%d') #Convert datetime to a string and use'%Y-%m-%d'Format output
print(s)print("===================================")"""
==================================2020-09-2200:00:002020-09-22=================================="""
**Write function: **
import time; #Introduce the time module
from pandas import DatetimeIndex
def date_range(cls, start=None, end=None, periods=None, freq=None, input_format=None, out_format=None):"""
Generate time series
: param start:Sequence start time
: param end:Sequence end time,When start is given,End time contains end
: param periods: int,The length of the generated time series
: param freq:The time interval to generate the time series
: param out_format:Whether to output the formatted string,Specify the output format for output."%Y-%m-%d %H:%M:%S":param input_format:If start or end is a string and the time format cannot be inferred automatically, you need to specify the format
: return:[date or date_str]"""
start = pd.to_datetime("20200918")
end = pd.to_datetime("20200922")
pd.date_range(start, end)DatetimeIndex(['2020-09-28','2020-09-29','2020-09-30','2020-09-13','2020-06-01','2020-06-02'])
Example 1:
# example 1:
dates =["20200912","20200922"]
def create_dates(dates):"""
: param dates:["20200912","20200922"]:return:"""
start = pd.to_datetime(dates[0])
end = pd.to_datetime(dates[1])
dates = pd.date_range(start, end) #Generate a list of time strings
dates = dates.strftime('%Y%m%d') #Format time data
returnlist(dates)print("example 1")print(create_dates(dates))"""
example 1['20200912','20200913','20200914','20200915','20200916','20200917','20200918','20200919','20200920','20200921','20200922']"""
**Example 2: **
# Example 2
df = pd.DataFrame({'year':[2019,2020],'month':[2,3],'day':[4,5]})
pd.to_datetime(df)print("Example 2")print(pd.to_datetime(df))"""
Example 202019-02-0412020-03-05
dtype: datetime64[ns]"""
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