Get date in Python

Purpose: Manipulate the date as you wish

I thought it would be necessary when manipulating the date of csv output by scraping in the future.

What you can get from this article

-You can specify the date in the csv name to be created by using the current time in the application. -Operation of csv written in the csv file -Date type to string type and vice versa

Output the current time

test.py

from datetime import datetime
now = datetime.now()
print(now)



-----result-----
2020-10-26 20:39:01.825495

How to change a string to a date

test.py

from datetime import datetime

#  2018/11/11 can be done in the same way
str_date = 'November 11, 2018'



#strptime turns a string into a date
#strftime turns the date into a string

one_date = datetime.strptime(str_date, '%Y year%m month%d day')
print(one_date)


-----result-----
2018-11-11 00:00:00

Past and future date manipulation

``test.py`

from datetime import datetime
from datetime import timedelta

str_date = '2018/11/11'
base_date = datetime.strptime(str_date, '%Y/%m/%d')

print(base_date)

-----result-----
2018-11-11 00:00:00
----------------


#10 days ago
before_10days = base_date - timedelta(days=10)
#10 days later
before_10days = base_date - timedelta(days=10)

print(before_10days)


-----result-----
2018-11-01 00:00:00

Manipulating dates using csv

day.csv

2016-10-01
2016-10-02
2016-10-03
2016-10-04
2016-10-05
2016-10-06
2016-10-07
2016-10-08
2016-10-09
2016-10-10
2016-10-11
2016-10-12
2016-10-13
2016-10-14

day.py

from datetime import datetime

#read csv
with open('day.csv', encoding='utf-8') as f:

    for row in f:
        day = datetime.strptime(row.rstrip(), '%Y-%m-%d')
        print(f'{day:%Y/%m/%d}')





-----result-----
2016/10/02
2016/10/03
2016/10/04
2016/10/05
2016/10/06
2016/10/07
2016/10/08
2016/10/09
2016/10/10
2016/10/11
2016/10/12
2016/10/13
2016/10/14

Python features

What's new in Python 3.8 f'{Expression =}' The expression itself can now be output. When outputting the format f'{expression =: format}'

Output the corresponding date from csv

test.py

from datetime import datetime
from datetime import timedelta

main_date ='2016-10-12'

#String → date
base_day = datetime.strptime(main_date,'%Y-%m-%d')

#Date one week ago
before_7days = base_day - timedelta(days=7)

#Select csv file
with open('day.csv', encoding='utf-8') as f:
 
    for row in f:

        #Character string → date Delete line break at the end of line
        day = datetime.strptime(row.rstrip(), '%Y-%m-%d')
        
        #print(day)
        #2016-10-02 00:00:00
        #2016-10-03 00:00:00
                #~
        #2016-10-14 00:00:00


        #2016-10-Show applicable items for 12 to 7 days
        if before_7days <= day < base_day:
                #Y/m/In d format
            print(f'{day:%Y/%m/%d}')


-----reult-----
2016/10/05
2016/10/06
2016/10/07
2016/10/08
2016/10/09
2016/10/10
2016/10/11