Creating a list of range of dates in Python

Last Updated : 23 Mar, 2023

Given a date, the task is to write a Python program to create a list of a range of dates with the next K dates starting from the current date.

Examples:

Input : test_date = datetime.datetime(1997, 1, 4), K = 5

Output : [datetime.datetime(1997, 1, 4), datetime.datetime(1997, 1, 5), datetime.datetime(1997, 1, 6), datetime.datetime(1997, 1, 7), datetime.datetime(1997, 1, 8)]

Explanation : 5 dates after 4 January are extracted in list.

Creating a list of dates using pd.date_range

In this method, we will use pandas date_range to create a list of ranges of dates in Python.

Python3

import datetime
import pandas as pd
 
# initializing date
test_date = datetime.datetime.strptime("01-7-2022", "%d-%m-%Y")
 
# initializing K 
K = 5
 
date_generated = pd.date_range(test_date, periods=K)
print(date_generated.strftime("%d-%m-%Y"))

Output:

Index(['01-07-2022', '02-07-2022', '03-07-2022', '04-07-2022', '05-07-2022'], dtype='object')

Creating a list of dates using timedelta() + list comprehension

In this, we get to add consecutive deltas to day using timedelta(), and list comprehension is used to iterate through the required size and construct the required result.

Python3

import datetime
 
# initializing date
test_date = datetime.datetime(1997, 1, 4)
 
# initializing K 
K = 5
 
# timedelta() gets successive dates with 
# appropriate difference
res = [test_date + datetime.timedelta(days=idx) for idx in range(K)]
 
# printing result
print("Next K dates list : " + str(res))

Output:

Next K dates list : [datetime.datetime(1997, 1, 4, 0, 0), datetime.datetime(1997, 1, 5, 0, 0),

datetime.datetime(1997, 1, 6, 0, 0), datetime.datetime(1997, 1, 7, 0, 0), datetime.datetime(1997, 1, 8, 0, 0)]

Creating a list of dates using Python Loop

In this, we perform a similar task as the above function, using a generator to perform the task of Date successions.

Python3

import datetime
 
start = datetime.date(2022,8,12)
 
# initializing K 
K = 5
 
res = []
 
for day in range(k):
    date = (start + datetime.timedelta(days = day)).isoformat()
    res.append(date)
     
# printing result
print("Next K dates list: " + str(res))

Output:

Next K dates list: ['2022-08-12', '2022-08-13', '2022-08-14', '2022-08-15', '2022-08-16']

Approach:

Import the required modules datetime and timedelta.
Define the start and end dates using the datetime module.
Initialize an empty list to store the generated dates.
Use a while loop that iterates through each day between the start and end dates.
Append each date to the date_list using the append method.
Increment the date by one day using the timedelta module.
Print the final date_list.

Python3

from datetime import datetime, timedelta
 
# Define start and end dates
start_date = datetime(2022, 3, 1)
end_date = datetime(2022, 3, 10)
 
# Initialize an empty list
date_list = []
 
# Loop through the range of dates and append to the list
while start_date <= end_date:
    date_list.append(start_date)
    start_date += timedelta(days=1)
 
# Print the list of dates
print(date_list)

Output

[datetime.datetime(2022, 3, 1, 0, 0), datetime.datetime(2022, 3, 2, 0, 0), datetime.datetime(2022, 3, 3, 0, 0), datetime.datetime(2022, 3, 4, 0, 0), datetime.datetime(2022, 3, 5, 0, 0), datetime.datetime(2022, 3, 6, 0, 0), datetime.datetime(2022, 3, 7, 0, 0), datetime.datetime(2022, 3, 8, 0, 0), datetime.datetime(2022, 3, 9, 0, 0), datetime.datetime(2022, 3, 10, 0, 0)]

This approach has a time complexity of O(n) where n is the number of dates in the range

An auxiliary space of O(n) to store the list of dates.

Using a generator and timedelta:

Approach steps:

Define the function date_range_4 that takes two arguments – test_date and K.
Initialize a variable i to 0.
Enter a loop that runs K times.
Inside the loop, yield the current date, i.e., test_date plus i days.
Increment i by 1 after each iteration.
Call the date_range_4 function with test_date and K as arguments.
Convert the generator object returned by the function to a list using the list() function.
Print the list of dates.

Python3

import datetime
 
def date_range_4(test_date, K):
    i = 0
    while i < K:
        yield test_date + datetime.timedelta(days=i)
        i += 1
 
test_date = datetime.datetime(1997, 1, 4)
K = 5
date_list = list(date_range_4(test_date, K))
print(date_list) # Output: [datetime.datetime(1997, 1, 4, 0, 0), datetime.datetime(1997, 1, 5, 0, 0), datetime.datetime(1997, 1, 6, 0, 0), datetime.datetime(1997, 1, 7, 0, 0), datetime.datetime(1997, 1, 8, 0, 0)]

Output

[datetime.datetime(1997, 1, 4, 0, 0), datetime.datetime(1997, 1, 5, 0, 0), datetime.datetime(1997, 1, 6, 0, 0), datetime.datetime(1997, 1, 7, 0, 0), datetime.datetime(1997, 1, 8, 0, 0)]

Time complexity: O(K)
Space complexity: O(1) (since the generator yields one date at a time without storing all the dates in memory)