在 python 中，如何创建列表列表，其中每个列表都包含开始和结束日期的字符串表示形式？

Question

My desired output would be this:

date_list = [
                ['2021-04-15', '2021-04-20'],
                ['2021-04-21', '2021-04-26'],
                ['2021-04-27', '2021-05-02'],
                ['2021-05-03', '2021-05-08'],
                ['2021-05-09', '2021-05-16'],
        ]

I would like to be able to define a start_date ('2021-04-15'), an end_date ('2021-05-16'), and an integer representing how many days I would like in each chunk (for example, I want each sub-list to contain a 5-day chunk). I also need to make sure that the end_date is included in the last list/chunk regardless of the size of that chunk. I need to be able to use the elements of each list to parameterize a SQL loop and have attempted many solutions and none have been even close to what I am looking for.

Answer 1

>>> import datetime
>>> start = datetime.datetime(year=2021, month=4, day=15)
>>> end = datetime.datetime(year=2021, month=5, day=16)
>>> delta = datetime.timedelta(days=5)
>>> result = []
>>> while start <= end:
        result.append([start.strftime('%Y-%m-%d'), (start+delta).strftime('%Y-%m-%d')])
        start += delta + datetime.timedelta(days=1)
>>> result
[['2021-04-15', '2021-04-20'],
 ['2021-04-21', '2021-04-26'],
 ['2021-04-27', '2021-05-02'],
 ['2021-05-03', '2021-05-08'],
 ['2021-05-09', '2021-05-14'],
 ['2021-05-15', '2021-05-20']]

Answer 2

This will work:

import datetime
import pandas as pd

def get_date_chunks(start_date, end_date, chunk_size):
    curr = datetime.datetime.strptime(start_date, "%Y-%m-%d")
    end_date = datetime.datetime.strptime(end_date, "%Y-%m-%d")
    offset = pd.DateOffset(days=chunk_size)
    result = []
    while curr <= end_date:
        result.append([str(curr.date()), str((curr + offset).date())])
        curr += pd.DateOffset(days = chunk_size + 1)
        
    # Make sure last date matches up with the end_date
    if datetime.datetime.strptime(result[-1][0], "%Y-%m-%d") > end_date:
        result.pop()
    else:
        result[-1][1] = str(end_date.date())
    return result 
    
get_date_chunks('2021-04-15', '2021-05-16', 5)

This line:

if datetime.datetime.strptime(result[-1][0], "%Y-%m-%d") > end_date:

Means that your final list could be ['2021-05-15', '2021-05-15'] , which guarentees that you will always include the end date, but you will never see a day beyond your end date.

Answer 3

This one does it exactly as you specified in your desired output. If the last chunk would be smaller than 5, it simply unites it with the previous one.

import datetime
from dateutil import parser

def create_date_list(start_date, end_date, chunk_size):
    start_date = parser.parse(start_date)
    end_date = parser.parse(end_date)
    
    dates = []
    
    i = 0
    while True:
        chunk_start = start_date + i*datetime.timedelta(chunk_size) + datetime.timedelta(i)
        chunk_end = chunk_start + datetime.timedelta(chunk_size)
        if (end_date - chunk_end).days <= chunk_size:
            dates.append([str(chunk_start).split()[0], str(end_date).split()[0]])
            break
        else:
            dates.append([str(chunk_start).split()[0], str(chunk_end).split()[0]])
        i += 1
    
    return dates