I've spent the past hour digging around the Python docs and many SO questions; please forgive me for being another Python newbie trapped by the mystery of time difference in Python.
My goal is to determine the difference between the current time and a certain date/time regardless of being in the past/future and return a workable format such as seconds.
For example, if the inputs are 2:00PM and 4:00PM (now), I'd like it to say "-7200", representing the event occurred two hours AGO. If the inputs are Fri 4:00PM (now) and Sun 5:00PM the output should be "176400" seconds, representing two days and 1 hour from now.
Here are the things I've tried...
My first version was a function that took a string timestamp and pieced it to multiple variables, and then compared them. It was clunky with many errors and I imagine if I posted it here I would be responsible for a programmers throwing up.
I stumbled upon this magical timedelta function and explored the docs and SO, but I don't think it does what I'm looking for.
I had the idea to convert both timestamps into seconds since epoch and then subtract, but this becomes a problem if the subtraction is in the wrong order (different cases if the event is in the future), and I feel like adding if statements to check the sign of the seconds would be clunky and something to avoid.
This is my current code (still needs to be fixed for 'bi-directional' comparison), from a previously resolved SO question:
now = time.strftime("%a %b %d %H:%M:%S %Y") then = time.ctime(os.path.getmtime("x.cache")) tdelta = datetime.strptime(now, '%a %b %d %H:%M:%S %Y') - datetime.strptime(then, '%a %b %d %H:%M:%S %Y')
And I feel like I should somehow be able to pull seconds from this, like in this question: Python's timedelta: can't I just get in whatever time unit I want the value of the entire difference?
But I am at a lost on how to connect these dots.
How can I accomplish this?
The date class is used to instantiate date objects in Python. When an object of this class is instantiated, it represents a date in the format YYYY-MM-DD. Constructor of this class needs three mandatory arguments year, month and date.
Use strftime() function of a datetime class The format codes are standard directives for mentioning in which format you want to represent datetime. For example, the %d-%m-%Y %H:%M:%S codes convert date to dd-mm-yyyy hh:mm:ss format.
In Python, we can easily format dates and datetime objects with the strftime() function. For example, to format a date as YYYY-MM-DD, pass “%Y-%m-%d” to strftime(). If you want to create a string that is separated by slashes (“/”) instead of dashes (“-“), pass “%Y/%m/%d” to strftime().
You should be able to use
tdelta.total_seconds()
to get the value you are looking for. This is because tdelta
is a timedelta
object, as is any difference between datetime
objects.
A couple of notes:
strftime
followed by strptime
is superfluous. You should be able to get the current datetime with datetime.now
.time.ctime
followed by strptime
is more work than needed. You should be able to get the other datetime
object with datetime.fromtimestamp
.So, your final code could be
now = datetime.now() then = datetime.fromtimestamp(os.path.getmtime("x.cache")) tdelta = now - then seconds = tdelta.total_seconds()
What's wrong with this method?
>>> from datetime import datetime >>> a = datetime.now() >>> b = datetime.now() # after a few seconds >>> delta = a-b >>> delta.total_seconds() -6.655989
Note that total_seconds
is only available in Python 2.7 <, but per the documentation is:
Equivalent to (
td.microseconds + (td.seconds + td.days * 24 * 3600) * 10**6) / 10**6
computed with true division enabled.
which yields the exact same result.
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