Period accepts datetime64 value

Added support for `datetime64` value for Period. Fixes #9054.

Author: jcrist

pandas/src/period.pyx

@@ -710,6 +710,10 @@ cdef class Period(object):
             dt = value
             if freq is None:
                 raise ValueError('Must supply freq for datetime value')
+        elif isinstance(value, np.datetime64):
+            dt = Timestamp(value)
+            if freq is None:
+                raise ValueError('Must supply freq for datetime value')
         elif isinstance(value, date):
             dt = datetime(year=value.year, month=value.month, day=value.day)
             if freq is None:

pandas/tseries/tests/test_period.py

@@ -226,7 +226,9 @@ def test_period_constructor(self):
 
         i1 = Period(date(2007, 1, 1), freq='M')
         i2 = Period(datetime(2007, 1, 1), freq='M')
+        i3 = Period(np.datetime64('2007-01-01'), freq='M')
         self.assertEqual(i1, i2)
+        self.assertEqual(i2, i3)
 
         i1 = Period('2007-01-01 09:00:00.001')
         expected = Period(datetime(2007, 1, 1, 9, 0, 0, 1000), freq='L')