How to Iterate over months between two dates in Python?

How to Iterate over months between two dates in Python

Iterating over months between two dates in Python can be done using the dateutil library’s rrule function.

The rrule function allows you to specify a recurrence rule for a date, and can be used to generate a list of dates that fit the rule.

In this case, we will use it to generate a list of all the months between two dates.

Here is an example of how to use the rrule function to iterate over the months between two dates:

from datetime import datetime
from dateutil.rrule import rrule, MONTHLY

start_date = datetime(2020, 1, 1)
end_date = datetime(2020, 12, 31)

for dt in rrule(MONTHLY, dtstart=start_date, until=end_date):
    print(dt.strftime("%Y-%m"))

In this example, we first import the necessary modules from the datetime and dateutil.rrule libraries.

We then define our start and end dates using the datetime function. In this case, we are starting on January 1st, 2020 and ending on December 31st, 2020.

Next, we use the rrule function to generate a list of dates.

We specify the recurrence rule as MONTHLY, and provide the start date and end date as dtstart and until arguments, respectively.

The rrule function returns an iterator, which we can use in a for loop.

In this example, we are iterating through the dates generated by the rrule function, and we are using the strftime method to format the date as a string in the format “YYYY-MM”. Each iteration of the loop will print out the month (as a string) for that date.

You can also use this similar logic to check for the date within the range of start_date and end_date

start_date = datetime(2020, 1, 1)
end_date = datetime(2020, 12, 31)

curr_date = datetime(2020,8,1)
if curr_date >= start_date and curr_date <= end_date:
    print("within range")
else:
    print("not within range")

It’s worth noting that the above examples will only work for dates within the same year, if you want to generate date range across different years then you will have to modify the examples accordingly.

Additionally, you can take this further by adding different conditions like finding the months between a range which are not in a specific month.

This could be useful if you want to find the months between your start and end date that don’t fall in a specific month.

from datetime import datetime
from dateutil.rrule import rrule, MONTHLY

start_date = datetime(2020, 1, 1)
end_date = datetime(2020, 12, 31)

exclude_month = 6  # i.e exclude all dates in the month of June

for dt in rrule(MONTHLY, dtstart=start_date, until=end_date):
    if dt.month != exclude_month:
        print(dt.strftime("%Y-%m"))

This code will print all the months between start_date and end_date, except for June. You can change the exclude_month variable to any month you want to exclude.

It’s also possible to iterate over the number of months between two dates, rather than the specific dates themselves.

You can use the relativedelta function from the dateutil library to find the difference between two dates in terms of months. Here’s an example:

from datetime import datetime
from dateutil.relativedelta import relativedelta

start_date = datetime(2020, 1, 1)
end_date = datetime(2021, 12, 31)

months_diff = relativedelta(end_date, start_date).months

for i in range(months_diff):
    curr_month = start_date + relativedelta(months=i)
    print(curr_month.strftime("%Y-%m"))

In this example, we first find the number of months between the two dates using the relativedelta function.

We then use a for loop to iterate from 0 to the number of months between the two dates.

Within the loop, we use the relativedelta function again to add the current number of months to the start date, which gives us the date for the current month.

Finally, we use the strftime method to format the date as a string in the format “YYYY-MM”, and print it out.

You could also use python’s built-in date.month and date.year property in combination with the for loop to achieve the same result.

start_date = datetime(2020, 1, 1)
end_date = datetime(2022, 2, 1)

year,month = start_date.year,start_date.month
while (year,month) != (end_date.year, end_date.month):
    print(datetime(year, month, 1).strftime("%Y-%m"))
    if month == 12:
        year += 1
        month = 1
    else:
        month += 1

In this example we use while loop and a tuple of (year, month) to represent the current date and check if it’s equal to the end date, if not we print the current date and increment the month by 1.

In all of these examples, you should be able to iterate over the months between two dates, and do something with the specific dates or number of months, depending on your needs.

Do let me know if you have any questions or if there is anything more I could do to help you.

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