test_datetime.py 文件源码

def test_datetime_casting_rules(self):
        # Cannot cast safely/same_kind between timedelta and datetime
        assert_(not np.can_cast('m8', 'M8', casting='same_kind'))
        assert_(not np.can_cast('M8', 'm8', casting='same_kind'))
        assert_(not np.can_cast('m8', 'M8', casting='safe'))
        assert_(not np.can_cast('M8', 'm8', casting='safe'))

        # Can cast safely/same_kind from integer to timedelta
        assert_(np.can_cast('i8', 'm8', casting='same_kind'))
        assert_(np.can_cast('i8', 'm8', casting='safe'))

        # Cannot cast safely/same_kind from float to timedelta
        assert_(not np.can_cast('f4', 'm8', casting='same_kind'))
        assert_(not np.can_cast('f4', 'm8', casting='safe'))

        # Cannot cast safely/same_kind from integer to datetime
        assert_(not np.can_cast('i8', 'M8', casting='same_kind'))
        assert_(not np.can_cast('i8', 'M8', casting='safe'))

        # Cannot cast safely/same_kind from bool to datetime
        assert_(not np.can_cast('b1', 'M8', casting='same_kind'))
        assert_(not np.can_cast('b1', 'M8', casting='safe'))
        # Can cast safely/same_kind from bool to timedelta
        assert_(np.can_cast('b1', 'm8', casting='same_kind'))
        assert_(np.can_cast('b1', 'm8', casting='safe'))

        # Can cast datetime safely from months/years to days
        assert_(np.can_cast('M8[M]', 'M8[D]', casting='safe'))
        assert_(np.can_cast('M8[Y]', 'M8[D]', casting='safe'))
        # Cannot cast timedelta safely from months/years to days
        assert_(not np.can_cast('m8[M]', 'm8[D]', casting='safe'))
        assert_(not np.can_cast('m8[Y]', 'm8[D]', casting='safe'))
        # Can cast datetime same_kind from months/years to days
        assert_(np.can_cast('M8[M]', 'M8[D]', casting='same_kind'))
        assert_(np.can_cast('M8[Y]', 'M8[D]', casting='same_kind'))
        # Can't cast timedelta same_kind from months/years to days
        assert_(not np.can_cast('m8[M]', 'm8[D]', casting='same_kind'))
        assert_(not np.can_cast('m8[Y]', 'm8[D]', casting='same_kind'))
        # Can't cast datetime same_kind across the date/time boundary
        assert_(not np.can_cast('M8[D]', 'M8[h]', casting='same_kind'))
        assert_(not np.can_cast('M8[h]', 'M8[D]', casting='same_kind'))
        # Can cast timedelta same_kind across the date/time boundary
        assert_(np.can_cast('m8[D]', 'm8[h]', casting='same_kind'))
        assert_(np.can_cast('m8[h]', 'm8[D]', casting='same_kind'))

        # Cannot cast safely if the integer multiplier doesn't divide
        assert_(not np.can_cast('M8[7h]', 'M8[3h]', casting='safe'))
        assert_(not np.can_cast('M8[3h]', 'M8[6h]', casting='safe'))
        # But can cast same_kind
        assert_(np.can_cast('M8[7h]', 'M8[3h]', casting='same_kind'))
        # Can cast safely if the integer multiplier does divide
        assert_(np.can_cast('M8[6h]', 'M8[3h]', casting='safe'))