Generate a random date between two other dates
How would I generate a random date that has to be between two other given dates?
The function's signature should be something like this:
random_date("1/1/2008 1:30 PM", "1/1/2009 4:50 AM", 0.34)
^ ^ ^
date generated has date generated has a random number
to be after this to be before this
and would return a date such as: 2/4/2008 7:20 PM
Convert both strings to timestamps (in your chosen resolution, e.g. milliseconds, seconds, hours, days, whatever), subtract the earlier from the later, multiply your random number (assuming it is distributed in the range [0, 1]
) with that difference, and add again to the earlier one. Convert the timestamp back to date string and you have a random time in that range.
Python example (output is almost in the format you specified, other than 0
padding - blame the American time format conventions):
import random
import time
def str_time_prop(start, end, time_format, prop):
"""Get a time at a proportion of a range of two formatted times.
start and end should be strings specifying times formatted in the
given format (strftime-style), giving an interval [start, end].
prop specifies how a proportion of the interval to be taken after
start. The returned time will be in the specified format.
"""
stime = time.mktime(time.strptime(start, time_format))
etime = time.mktime(time.strptime(end, time_format))
ptime = stime + prop * (etime - stime)
return time.strftime(time_format, time.localtime(ptime))
def random_date(start, end, prop):
return str_time_prop(start, end, '%m/%d/%Y %I:%M %p', prop)
print(random_date("1/1/2008 1:30 PM", "1/1/2009 4:50 AM", random.random()))
from random import randrange
from datetime import timedelta
def random_date(start, end):
"""
This function will return a random datetime between two datetime
objects.
"""
delta = end - start
int_delta = (delta.days * 24 * 60 * 60) + delta.seconds
random_second = randrange(int_delta)
return start + timedelta(seconds=random_second)
The precision is seconds. You can increase precision up to microseconds, or decrease to, say, half-hours, if you want. For that just change the last line's calculation.
example run:
from datetime import datetime
d1 = datetime.strptime('1/1/2008 1:30 PM', '%m/%d/%Y %I:%M %p')
d2 = datetime.strptime('1/1/2009 4:50 AM', '%m/%d/%Y %I:%M %p')
print(random_date(d1, d2))
output:
2008-12-04 01:50:17