Check if the date is valid somewhere in the world

How can you check if a given time stamp is saved anywhere in the world?

For example, let's say that I have a timestamp similar to May 10, 2017 3:49 pm. Is there a place in the world today for which May 10, 2017, 3:49 pm?

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3 answers


Check if there is a timestamp between UTC + 14 and UTC-12.

from datetime import datetime, timedelta

def is_a_today_somewhere(timestamp):
  now = datetime.now()
  latest = now + timedelta(hours=-12)
  earliest = now + timedelta(hours=14)
  return  latest <= datetime.fromtimestamp(timestamp) <= earliest

now = datetime.now()                        # now
timestamp = datetime.timestamp(now)
print(is_a_today_somewhere(timestamp))      # prints True

now = datetime.now() + timedelta(hours=7)   # +7 hours from now
timestamp = datetime.timestamp(now)
print(is_a_today_somewhere(timestamp))      # prints True

now = datetime.now() + timedelta(hours=-23) # -23 hours from now
timestamp = datetime.timestamp(now)
print(is_a_today_somewhere(timestamp))      # prints False

      

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Please note that verification must be enabled. But due to the time it takes to create a timestamp to validate it, edge cases where the timestamp is barely in the last timezone can appear false.

from datetime import datetime, timedelta

def is_a_today_somewhere(timestamp):
  now = datetime.now()
  latest = now + timedelta(hours=-12)
  earliest = now + timedelta(hours=14)
  return  latest <= datetime.fromtimestamp(timestamp) <= earliest

now = datetime.now() + timedelta(hours=-12)  # -12 hours from now; barely in today 
timestamp = datetime.timestamp(now)
print(is_a_today_somewhere(timestamp))      # May print False

      

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You can check by comparing the current time in all time zones with the time provided.

Here's a function to do it for you:



import datetime
deviations_from_utc = (-12, -11, -10, -9.5, -9, -8, -7, -6, -5,
                   -4, -3.5, -3, -2, -1, 0, 1, 2, 3, 3.5, 4, 4.5, 5,
                   5.5, 5.75, 6, 6.5, 7, 8, 8.5, 8.75, 9, 9.5, 10, 
                   10.5, 11, 12 , 12.75, 13, 14)
def is_current(t):
    n = datetime.datetime.utcnow()
    provided_time = (t.year, t.month, t.day, t.hour, t.minute)
    for time in deviations_from_utc:
        at = n + datetime.timedelta(hours=time)
        at_time = (at.year, at.month, at.day, at.hour, at.minute)
        if provided_time == at_time:
            return True
    return False

      

deviations_from_utc contains all deviations from utc times that are in use. The list was taken from this wikipedia article.

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By using the standard deviations from UTC ie a maximum of +14 and a minimum of -12, you can compare the timestamps and see if the timestamp is between the maximum and minimum.

from datetime import datetime


def is_valid_time(search_timestamp):
    utc_timestamp = datetime.timestamp(datetime.utcnow())
    max_timestamp = utc_timestamp + (14*60*60)  # max time is utc+14
    min_timestamp = utc_timestamp - (12*60*60)  # min time is utc-12

    # check if time in range
    if min_timestamp <= search_timestamp <= max_timestamp:
        return True
    return False

# Test cases
now = datetime.timestamp(datetime.now())
# false
print(is_valid_time(3))

# false
print(is_valid_time(now + (16*60*60)))

# true
print(is_valid_time(now))

      

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