Converting unix timestamp (length 13) string to readable date in Python

i am tring to convert this unix timestamp 1491613677888 to readable date. found here (stackoverflow) that python script:

import datetime
print(
    datetime.datetime.fromtimestamp(
    int("1284101485")
    ).strftime('%Y-%m-%d %H:%M:%S')
)

but when i put my timestamp there, i got that error:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
OSError: [Errno 22] Invalid argument

now i see that the timestamp that i am using is 3 chars longer. i checked it on this link: http://www.unixtimestamp.com/index.php

and saw that its get the time out of it. how can i do it using python? (i am using python 3.4)

Solution

Your timestamp is not the 'classical' Unix timestamp (number of seconds since Jan 1st, 1970), as it is expressed in milliseconds.

You can translate it like this:

import datetime

timestamp_with_ms = 1491613677888

# We separate the 'ordinary' timestamp and the milliseconds
timestamp, ms = divmod(timestamp_with_ms, 1000)
#1491613677 888

# We create the datetime from the timestamp, we must add the 
# milliseconds separately
dt = datetime.datetime.fromtimestamp(timestamp) + datetime.timedelta(milliseconds=ms)


formatted_time = dt.strftime('%Y-%m-%d %H:%M:%S.%f')[:-3]
# With Python 3.6, you could use:
# formatted_time = dt.isoformat(sep=' ', timespec='milliseconds')

print(formatted_time)
# 2017-04-08 03:07:57.888

Edit: I hadn't noticed that fromtimestamp accepts a float. So, we can simply do:

import datetime
timestamp_with_ms = 1491613677888

dt = datetime.datetime.fromtimestamp(timestamp_with_ms / 1000)

formatted_time = dt.strftime('%Y-%m-%d %H:%M:%S.%f')[:-3]
# With Python 3.6, you could use:
# formatted_time = dt.isoformat(sep=' ', timespec='milliseconds')

print(formatted_time)
# 2017-04-08 03:07:57.888