Generate a random date between two other dates

Question

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

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A tiny version   import datetime import random   def random date start  end          Generate a random datetime between  start  and  end         return start   datetime timedelta            Get a random amount of seconds between  start  and  end          seconds random randint 0  int  end - start  total seconds              Note that both start and end arguments should be datetime objects  If you ve got strings instead  it s fairly easy to convert  The other answers point to some ways to do so

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Use ApacheCommonUtils to generate a random long within a given range  and then create Date out of that long    Example   import org apache commons math random RandomData   import org apache commons math random RandomDataImpl   public Date nextDate Date min  Date max     RandomData randomData   new RandomDataImpl     return new Date randomData nextLong min getTime    max getTime

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Since Python 3 timedelta supports multiplication with floats  so now you can do   import random random date   start    end - start    random random     given that start and end are of the type datetime datetime  For example  to generate a random datetime within the next day   import random from datetime import datetime  timedelta  start   datetime now   end   start   timedelta days 1  random date   start    end - start    random random

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Updated answer  It s even more simple using Faker   Installation  pip install faker   Usage   from faker import Faker fake   Faker    fake date between start date  today   end date   30y     datetime date 2025  3  12   fake date time between start date  -30y   end date  now     datetime datetime 2007  2  28  11  28  16     Or if you need a more specific date boundaries  provide the start    and end dates explicitly  import datetime start date   datetime date year 2015  month 1  day 1  fake date between start date start date  end date   30y     Old answer  It s very simple using radar  Installation  pip install radar   Usage  import datetime  import radar     Generate random datetime  parsing dates from str values  radar random datetime start  2000-05-24   stop  2013-05-24T23 59 59      Generate random datetime from datetime datetime values radar random datetime      start   datetime datetime year 2000  month 5  day 24       stop   datetime datetime year 2013  month 5  day 24       Just render some random datetime  If no range is given  start defaults to    1970-01-01 and stop defaults to datetime datetime now   radar random datetime

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start timestamp   time mktime time strptime  Jun 1 2010  01 33 00     b  d  Y  I  M  S    end timestamp   time mktime time strptime  Jun 1 2017  12 33 00     b  d  Y  I  M  S    time strftime   b  d  Y  I  M  S  time localtime randrange start timestamp end timestamp      refer

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To chip in a pandas-based solution I use   import pandas as pd import numpy as np  def random date start  end  position None       start  end   pd Timestamp start   pd Timestamp end      delta    end - start  total seconds       if position is None          offset   np random uniform 0   delta      else          offset   position   delta     offset   pd offsets Second offset      t   start   offset     return t   I like it  because of the nice pd Timestamp features that allow me to throw different stuff and formats at it  Consider the following few examples     Your signature    gt  gt  gt  random date start  1 1 2008 1 30 PM   end  1 1 2009 4 50 AM   position 0 34  Timestamp  2008-05-04 21 06 48   tz None    Random position    gt  gt  gt  random date start  1 1 2008 1 30 PM   end  1 1 2009 4 50 AM   Timestamp  2008-10-21 05 30 10   tz None    Different format    gt  gt  gt  random date  2008-01-01 13 30    2009-01-01 4 50   Timestamp  2008-11-18 17 20 19   tz None    Passing pandas datetime objects directly    gt  gt  gt  random date pd datetime now    pd datetime now     pd offsets Hour 3   Timestamp  2014-03-06 14 51 16 035965   tz None

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It s modified method of   Tom Alsberg   I modified it to get date with milliseconds   import random import time import datetime  def random date start time string  end time string  format string  random number               Get a time at a proportion of a range of two formatted times      start and end should be strings specifying times formated 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              dt start   datetime datetime strptime start time string  format string      dt end   datetime datetime strptime end time string  format string       start time   time mktime dt start timetuple      dt start microsecond   1000000 0     end time   time mktime dt end timetuple      dt end microsecond   1000000 0      random time   start time   random number    end time - start time       return datetime datetime fromtimestamp random time  strftime format string    Example   print TestData TestData random date  2000 01 01 00 00 00 000000    2049 12 31 23 59 59 999999     Y  m  d  H  M  S  f   random random      Output  2028 07 08 12 34 49 977963

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Based on the answer by mouviciel  here is a vectorized solution using numpy  Convert the start and end dates to ints  generate an array of random numbers between them  and convert the whole array back to dates    import time import datetime import numpy as np  n rows   10  start time    01 12 2011  end time    05 08 2017   date2int   lambda s  time mktime datetime datetime strptime s   d  m  Y   timetuple    int2date   lambda s  datetime datetime fromtimestamp s  strftime   Y- m- d  H  M  S    start time   date2int start time  end time   date2int end time   random ints   np random randint low start time  high end time  size  n rows 1   random dates   np apply along axis int2date  1  random ints  reshape n rows 1   print random dates

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This is a different approach - that sort of works    from random import randint import datetime  date datetime date randint 2005 2025   randint 1 12  randint 1 28     BETTER APPROACH  startdate datetime date YYYY MM DD  date startdate datetime timedelta randint 1 365

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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

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What do you need the random number for  Usually  depending on the language  you can get the number of seconds milliseconds from the Epoch from a date  So for a randomd date between startDate and endDate you could do    compute the time in ms between startDate and endDate  endDate toMilliseconds   - startDate toMilliseconds    generate a number between 0 and the number you obtained in 1 generate a new Date with time offset   startDate toMilliseconds     number obtained in 2

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needed to create data for 1000 fictitious employees for testing code    code relating to randomly assigning forenames  surnames  and genders   has been removed as not germaine to the question asked above but FYI   genders were randomly assigned  forenames surnames were web scrapped    there is no accounting for leap years  and the data stored in mySQL     import random  from datetime import datetime from datetime import timedelta  for employee in range 1000         assign a random date of birth  employees are aged between sixteen and sixty five      dlt   random randint 365 16  365 65      dob   datetime today   - timedelta days dlt        assign a random date of hire sometime between sixteenth birthday and yesterday     doh   datetime today   - timedelta days random randint 1  dlt-365 16       print  quot born    hired    quot  format dob strftime  quot  d- m- y quot    doh strftime  quot  d- m- y quot

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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  format  prop          Get a time at a proportion of a range of two formatted times       start and end should be strings specifying times formated 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  format       etime   time mktime time strptime end  format        ptime   stime   prop    etime - stime       return time strftime 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

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Here s a solution modified from emyller s approach which returns an array of random dates at any resolution  import numpy as np  def random dates start  end  size 1  resolution  s                Returns an array of random dates in the interval  start  end   Valid      resolution arguments are numpy date time units  as documented at           https   docs scipy org doc numpy-dev reference arrays datetime html             start  end   np datetime64 start   np datetime64 end      delta    end-start  astype  timedelta64      format resolution       delta mat   np random randint 0  delta astype  int    size      return start   delta mat astype  timedelta64      format resolution     Part of what s nice about this approach is that np datetime64 is really good at coercing things to dates  so you can specify your start end dates as strings  datetimes  pandas timestamps    pretty much anything will work

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Pandas   numpy solution  import pandas as pd import numpy as np  def RandomTimestamp start  end       dts    end - start  total seconds       return start   pd Timedelta np random uniform 0  dts    s     dts is the difference between timestamps in seconds  float   It is then used to create a pandas timedelta between 0 and dts  that is added to the start timestamp

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Conceptually it s quite simple   Depending on which language you re using you will be able to convert those dates into some reference 32 or 64 bit integer  typically representing seconds since epoch  1 January 1970  otherwise known as  Unix time  or milliseconds since some other arbitrary date   Simply generate a random 32 or 64 bit integer between those two values   This should be a one liner in any language   On some platforms you can generate a time as a double  date is the integer part  time is the fractional part is one implementation    The same principle applies except you re dealing with single or double precision floating point numbers   floats  or  doubles  in C  Java and other languages    Subtract the difference  multiply by random number  0  lt   r  lt   1   add to start time and done

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Here is an answer to the literal meaning of the title rather than the body of this question   import time import datetime import random  def date to timestamp d      return int time mktime d timetuple      def randomDate start  end        Get a random date between two dates       stime   date to timestamp start    etime   date to timestamp end     ptime   stime   random random      etime - stime     return datetime date fromtimestamp ptime    This code is based loosely on the accepted answer

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In python    gt  gt  gt  from dateutil rrule import rrule  DAILY  gt  gt  gt  import datetime  random  gt  gt  gt  random choice                   list                       rrule DAILY                              dtstart datetime date 2009 8 21                               until datetime date 2010 10 12                                             datetime datetime 2010  2  1  0  0     need python dateutil library     pip install python-dateutil

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usr bin env python   - - coding  utf-8 - -     Create random datetime object      from datetime import datetime import random   def create random datetime from date  to date  rand type  uniform                Create random date within timeframe       Parameters     ----------     from date   datetime object     to date   datetime object     rand type     uniform        Examples     --------      gt  gt  gt  random seed 28041990       gt  gt  gt  create random datetime datetime 1990  4  28   datetime 2000  12  31       datetime datetime 1998  12  13  23  38  0  121628       gt  gt  gt  create random datetime datetime 1990  4  28   datetime 2000  12  31       datetime datetime 2000  3  19  19  24  31  193940              delta   to date - from date     if rand type     uniform           rand   random random       else          raise NotImplementedError  Unknown random mode                                            format rand type       return from date   rand   delta   if   name         main         import doctest     doctest testmod

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You can Use Mixer   pip install mixer   and   from mixer import generators as gen print gen get datetime min datetime  1900  1  1  0  0  0   max datetime  2020  12  31  23  59  59

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I made this for another project using random and time  I used a general format from time you can view the documentation here for the first argument in strftime    The second part is a random randrange function  It returns an integer between the arguments  Change it to the ranges that match the strings you would like  You must have nice arguments in the tuple of the second arugment   import time import random   def get random date        return strftime   Y- m- d  H  M  S   random randrange 2000 2016  random randrange 1 12       random randrange 1 28  random randrange 1 24  random randrange 1 60  random randrange 1 60  random randrange 1 7  random randrange 0 366  1

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Just to add another one   datestring   datetime datetime strftime datetime datetime        random randint 2000  2015         random randint 1  12         random randint 1  28         random randrange 23         random randrange 59         random randrange 59         random randrange 1000000      Y- m- d  H  M  S     The day handling needs some considerations  With 28 you are on the secure site

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Alternative way to create random dates between two dates using np random randint    pd Timestamp   value and pd to datetime   with for loop    Import libraries import pandas as pd    Initialize start    2020-01-01    Specify start date end    2020-03-10    Specify end date n   10   Specify number of dates needed    Get random dates x   np random randint pd Timestamp start  value  pd Timestamp end  value n  random dates    pd to datetime  i 10  9   60 60  24  unit  D   strftime   Y- m- d    for i in x   print random dates   Output   2020-01-06     2020-03-08     2020-01-23     2020-02-03     2020-01-30     2020-01-05     2020-02-16     2020-03-08     2020-02-09     2020-01-04

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Convert your dates into timestamps and call random randint with the timestamps  then convert the randomly generated timestamp back into a date  from datetime import datetime import random  def random date first date  second date       first timestamp   int first date timestamp        second timestamp   int second date timestamp        random timestamp   random randint first timestamp  second timestamp      return datetime fromtimestamp random timestamp   Then you can use it like this from datetime import datetime  d1   datetime strptime  quot 1 1 2018 1 30 PM quot    quot  m  d  Y  I  M  p quot   d2   datetime strptime  quot 1 1 2019 4 50 AM quot    quot  m  d  Y  I  M  p quot    random date d1  d2   random date d2  d1     ValueError because the first date comes after the second date  If you care about timezones you should just use date time between dates from the Faker library  where I stole this code from  as a different answer already suggests

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Convert your input dates to numbers  int  float  whatever is best for your usage  Choose a number between your two date numbers  Convert this number back to a date    Many algorithms for converting date to and from numbers are already available in many operating systems

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The easiest way of doing this is to convert both numbers to timestamps  then set these as the minimum and maximum bounds on a random number generator   A quick PHP example would be      Find a randomDate between  start date and  end date function randomDate  start date   end date           Convert to timetamps      min   strtotime  start date        max   strtotime  end date           Generate random number using above bounds      val   rand  min   max           Convert back to desired date format     return date  Y-m-d H i s    val       This function makes use of strtotime   to convert a datetime description into a Unix timestamp  and date   to make a valid date out of the random timestamp which has been generated

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Get random date between start date and end date  If any of them is None  then get random date between today and past 100 years  class GetRandomDateMixin      def get random date self  start date None  end date None            quot  quot  quot          get random date between start date and end date          If any of them is None  then get random date between         today and past 100 years           param start date  datetime obj              eg  datetime datetime 1940  1  1  date            param end date  datetime obj          return  random date          quot  quot  quot          if start date is None or end date is None               end date   datetime datetime today   date               start date   end date - datetime timedelta                  days  100   365                         delta   end date - start date         random days   random randint 1  delta days          new date   start date   datetime timedelta              days random days                    return new date

[python] Generate a random date between two other dates

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