Equivalent function of datenum(datestring) of Matl

Question

In Matlab, when I run "datenum" function as the following;

datenum(1970, 1, 1);

I get the following output:

719529

I'm trying to find the equivalent function or script which is gonna give me the same output. But, unfortunately I couldn't find an enough explanation on the internet to do this.

I have looked at this tutorial: https://docs.python.org/2/library/datetime.html, but it didn't help.

Could you tell me, how can I get the same output in python?

Thanks,

Answer 1

You can substract date objects in Python:

>>> date(2015, 10, 7) - date(1, 1, 1)
datetime.timedelta(735877)

>>> (date(2015, 10, 7) - date(1, 1, 1)).days
735877

Just take care to use an epoch that is useful to your needs.

Answer 2

I would use the datetime module and the toordinal() function

from datetime import date

print date.toordinal(date(1970,1,1))

719163

To get the date you got you would use

print date.toordinal(date(1971,1,2))

719529

or for easier conversion

print date.toordinal(date(1970,1,1))+366

719529

I believe the reason the date is off is due to the fact datenum starts its counting from january 0, 0000 which this doesn't recognize as a valid date. You will have to counteract the change in the starting date by adding one to the year and day. The month doesn't matter because the first month in datetime is equal to 0 in datenum

Answer 3

The previous answers return an integer. MATLAB's datenum does not necessarily return an integer. The following code retuns the same answer as MATLAB's datenum:

from datetime import datetime as dt

def datenum(d):
    return 366 + d.toordinal() + (d - dt.fromordinal(d.toordinal())).total_seconds()/(24*60*60)

d = dt.strptime('2019-2-1 12:24','%Y-%m-%d %H:%M')
dn = datenum(d)