Date & time conversions used in the sciences. The assumption is that datetimes are timezone-naive, as this is required in Numpy et al for numpy.datetime64.

python -m pip install sciencedates

import sciencedates as sd

T = '2013-07-02T12'
yeardoy, utsec = sd.datetime2yd(T)

Results in year,DayOfYear; UTC fraction of day [seconds]

(2013102, 72000.0)

Julia examples are provided

Matlab / GNU Octave examples are provided

Fortran examples are provided. For Python-like modern Fortran datetime, see Datetime-Fortran.