ENH: Timestamp: Support addl datetime classmethods

* `utcfromtimestamp`,`timestamp`, and `combine` now supported
* Closes pandas-dev#5351.

Author: jtratner

doc/source/whatsnew/v0.15.2.txt

@@ -43,6 +43,7 @@ Enhancements
 
 - Added ability to export Categorical data to Stata (:issue:`8633`).
 - Added ability to export Categorical data to to/from HDF5 (:issue:`7621`). Queries work the same as if it was an object array. However, the ``category`` dtyped data is stored in a more efficient manner. See :ref:`here <io.hdf5-categorical>` for an example and caveats w.r.t. prior versions of pandas.
+- Added support for ``utcfromtimestamp()``, ``fromtimestamp()``, and ``combine()`` on `Timestamp` class (:issue:`5351`).
 
 .. _whatsnew_0152.performance:
 

pandas/tseries/tests/test_timeseries.py

@@ -1,4 +1,5 @@
 # pylint: disable-msg=E1101,W0612
+import calendar
 from datetime import datetime, time, timedelta
 import sys
 import operator
@@ -3291,6 +3292,16 @@ def compare(x, y):
         compare(Timestamp.now('UTC'), datetime.now(timezone('UTC')))
         compare(Timestamp.utcnow(), datetime.utcnow())
         compare(Timestamp.today(), datetime.today())
+        current_time = calendar.timegm(datetime.now().utctimetuple())
+        compare(Timestamp.utcfromtimestamp(current_time),
+                datetime.utcfromtimestamp(current_time))
+        compare(Timestamp.fromtimestamp(current_time),
+                datetime.fromtimestamp(current_time))
+
+        date_component = datetime.utcnow()
+        time_component = (date_component + timedelta(minutes=10)).time()
+        compare(Timestamp.combine(date_component, time_component),
+                datetime.combine(date_component, time_component))
 
     def test_class_ops_dateutil(self):
         tm._skip_if_no_dateutil()
@@ -3303,6 +3314,16 @@ def compare(x,y):
         compare(Timestamp.now('UTC'), datetime.now(tzutc()))
         compare(Timestamp.utcnow(),datetime.utcnow())
         compare(Timestamp.today(),datetime.today())
+        current_time = calendar.timegm(datetime.now().utctimetuple())
+        compare(Timestamp.utcfromtimestamp(current_time),
+                datetime.utcfromtimestamp(current_time))
+        compare(Timestamp.fromtimestamp(current_time),
+                datetime.fromtimestamp(current_time))
+
+        date_component = datetime.utcnow()
+        time_component = (date_component + timedelta(minutes=10)).time()
+        compare(Timestamp.combine(date_component, time_component),
+                datetime.combine(date_component, time_component))
 
     def test_basics_nanos(self):
         val = np.int64(946684800000000000).view('M8[ns]')

pandas/tslib.pyx

@@ -228,6 +228,17 @@ class Timestamp(_Timestamp):
     def utcnow(cls):
         return cls.now('UTC')
 
+    @classmethod
+    def utcfromtimestamp(cls, ts):
+        return cls(datetime.utcfromtimestamp(ts))
+
+    @classmethod
+    def fromtimestamp(cls, ts):
+        return cls(datetime.fromtimestamp(ts))
+
+    @classmethod
+    def combine(cls, date, time):
+        return cls(datetime.combine(date, time))
 
     def __new__(cls, object ts_input, object offset=None, tz=None, unit=None):
         cdef _TSObject ts