将日期传递给列表

Question

I'm attempting to generate random start and end dates with the end date being greater than the start date and pass the results to a list. I've tried a for loop but its not working as expected. Below is the code I'm using and the desired output I'm looking for.

"""Generate random dates where end date is greater than start date
   and append to list
"""
import random
from datetime import date

start = date(2019, 1, 1)
end = date(2019, 12, 31)

for i in range(27):
    random_start_date = start + (end - start) * random.random()
    random_end_date = random_start_date + (end - random_start_date) * random.random()
    #Converting to string in order to append to list
    start_dates = random_start_date.strftime('%Y-%m-%d')
    end_dates = random_end_date.strftime('%Y-%m-%d')
    print(start_dates, end_dates)


#Current output
2019-01-01 2019-02-01
2019-02-01 2019-03-01
2019-05-21 2019-05-31

#Desired output
[2019-01-01, 2019-02-01, 2019-05-21]
[2019-02-01, 2019-03-01, 2019-05-31]

Answer 1

You've got two problems there.

The first is that you aren't appending to your list, you're replacing it, the second is you are printing every time through the loop rather than at the end.

Try this:

start_dates=[]
end_dates=[]
for i in range(27):
    random_start_date = start + (end - start) * random.random()
    random_end_date = random_start_date + (end - random_start_date) * random.random()
    #Converting to string in order to append to list
    start_dates.append(random_start_date.strftime('%Y-%m-%d'))
    end_dates.append(random_end_date.strftime('%Y-%m-%d'))
print(start_dates, end_dates, sep='\n')

(The sep='\n' puts each argument to print() on a new line.)