Calculate the total days between a range of dates using Python

I have a list of date ranges and want to find the total number of days between those ranges. However, the ranges may, or may not, have overlap. And I want to exclude overlapped time. There may also be gaps between the ranges which I also want to exclude.

I’m curious on the most optimal way to calculate this.

An example:

ranges = [
{'start': 1/1/2001, 'end': 1/1/2002},
{'start': 1/1/2000, 'end': 1/1/2002},
{'start': 1/1/2003, 'end': 1/1/2004},
]

Total range time in days — 1/1/2000 through 1/1/2002 + 1/1/2003 through 1/1/2004

Answer

from datetime import datetime, timedelta

ranges = [
    {'start': '1/1/2001', 'end': '1/1/2002'},
    {'start': '1/1/2000', 'end': '1/1/2002'},
    {'start': '1/1/2003', 'end': '1/1/2004'},
]

# Sort the list of date ranges by the start date
ranges = sorted(ranges, key=lambda x: datetime.strptime(x['start'], '%m/%d/%Y'))

# Initialize the start and end dates for the non-overlapping and non-gapped ranges
start_date = datetime.strptime(ranges[0]['start'], '%m/%d/%Y')
end_date = datetime.strptime(ranges[0]['end'], '%m/%d/%Y')
total_days = 0

# Iterate through the list of date ranges
for i in range(1, len(ranges)):
    current_start_date = datetime.strptime(ranges[i]['start'], '%m/%d/%Y')
    current_end_date = datetime.strptime(ranges[i]['end'], '%m/%d/%Y')

    # Check for overlaps and gaps
    if current_start_date <= end_date:
        end_date = max(end_date, current_end_date)
    else:
        total_days += (end_date - start_date).days
        start_date = current_start_date
        end_date = current_end_date

# Add the last range to the total days
total_days += (end_date - start_date).days
print(total_days)