ENH: timedelta64 mod and floordiv

timedelta64 mod and divmod do not support numeric other. floordiv behaves as expected:

td = pd.Timedelta(3456789)
td64 = td.to_timedelta64()

>>> divmod(td64, 2)
numpy.core._exceptions.UFuncTypeError: ufunc 'divmod' cannot use operands with types dtype('<m8[ns]') and dtype('int64')

>>> td64 % 2
numpy.core._exceptions.UFuncTypeError: ufunc 'remainder' cannot use operands with types dtype('<m8[ns]') and dtype('int64')

>>> td64 // 2
numpy.timedelta64(1728394,'ns')

>>> divmod(td, 2)
(Timedelta('0 days 00:00:00.001728394'), Timedelta('0 days 00:00:00.000000001'))

In pandas we implement mod and divmod in terms of floordiv (https://github.com/pandas-dev/pandas/blob/master/pandas/_libs/tslibs/timedeltas.pyx#L1440). I’d be happy to port this (and the accompanying tests) upstream if numpy is interested.

[jbrockmendel]

thanks, ill take a look. if you want to build off of pandas tests, the relevant ones would be in pandas/tests/arithmetic/test_timedelta64.py and pandas/tests/scalar/timedelta/test_arithmetic.py

[mattip]

that no BLAS seems like bad general advice to be honest.

I will try to expand the error message. My use case was a drive-by NumPy contributor who wants to fix an issue and tries to locally compile.:

If you have built locally, you should either install OpenBLAS or build NumPy
with a dummy, slow BLAS backend via
export NPY_BLAS_ORDER=""; 
export NPY_LAPACK_ORDER="";
rm -rf build; 
then rebuild numpy"