ENH: Cleaning up object <-> datetime conversions

4 files changed, 44 insertions, 3 deletions

diff --git a/numpy/core/src/multiarray/_datetime.h b/numpy/core/src/multiarray/_datetime.h
index 1f835ebff..84fb6fd9a 100644
--- a/numpy/core/src/multiarray/_datetime.h
+++ b/numpy/core/src/multiarray/_datetime.h
@@ -139,7 +139,7 @@ convert_pydatetime_to_datetimestruct(PyObject *obj, npy_datetimestruct *out);
  * Returns -1 on error, 0 on success.
  */
 NPY_NO_EXPORT int
-convert_pyobject_to_datetime(PyObject *obj, PyArray_DatetimeMetaData *meta,
+convert_pyobject_to_datetime(PyArray_DatetimeMetaData *meta, PyObject *obj,
                                 npy_datetime *out);
 
 /*
diff --git a/numpy/core/src/multiarray/arraytypes.c.src b/numpy/core/src/multiarray/arraytypes.c.src
index 4fe5ea19e..80bd59636 100644
--- a/numpy/core/src/multiarray/arraytypes.c.src
+++ b/numpy/core/src/multiarray/arraytypes.c.src
@@ -1110,7 +1110,7 @@ DATETIME_setitem(PyObject *op, char *ov, PyArrayObject *ap) {
     }
 
     /* Convert the object into a NumPy datetime */
-    if (convert_pyobject_to_datetime(op, meta, &temp) < 0) {
+    if (convert_pyobject_to_datetime(meta, op, &temp) < 0) {
         return -1;
     }
 
diff --git a/numpy/core/src/multiarray/datetime.c b/numpy/core/src/multiarray/datetime.c
index 02a5a4d59..accadf7c5 100644
--- a/numpy/core/src/multiarray/datetime.c
+++ b/numpy/core/src/multiarray/datetime.c
@@ -610,6 +610,10 @@ convert_datetime_to_datetimestruct(PyArray_DatetimeMetaData *meta,
     if (meta->events > 1) {
         out->event = dt % meta->events;
         dt = dt / meta->events;
+        if (out->event < 0) {
+            out->event += meta->events;
+            --dt;
+        }
     }
 
     /* TODO: Change to a mechanism that avoids the potential overflow */
@@ -2479,7 +2483,7 @@ invalid_time:
  * Returns -1 on error, 0 on success.
  */
 NPY_NO_EXPORT int
-convert_pyobject_to_datetime(PyObject *obj, PyArray_DatetimeMetaData *meta,
+convert_pyobject_to_datetime(PyArray_DatetimeMetaData *meta, PyObject *obj,
                                 npy_datetime *out)
 {
     if (PyBytes_Check(obj) || PyUnicode_Check(obj)) {
@@ -2525,6 +2529,31 @@ convert_pyobject_to_datetime(PyObject *obj, PyArray_DatetimeMetaData *meta,
         *out = PyLong_AsLongLong(obj);
         return 0;
     }
+    /* Could be a tuple with event number in the second entry */
+    else if (PyTuple_Check(obj) && PyTuple_Size(obj) == 2) {
+        int event, event_old;
+        if (convert_pyobject_to_datetime(meta, PyTuple_GET_ITEM(obj, 0),
+                                                                out) < 0) {
+            return -1;
+        }
+        event = (int)PyInt_AsLong(PyTuple_GET_ITEM(obj, 1));
+        if (event == -1 && PyErr_Occurred()) {
+            return -1;
+        }
+        if (event < 0 || event >= meta->events) {
+            PyErr_SetString(PyExc_ValueError, "event value for NumPy "
+                            "datetime is out of range");
+            return -1;
+        }
+        /* Replace the event with the one from the tuple */
+        event_old = *out % meta->events;
+        if (event_old < 0) {
+            event_old += meta->events;
+        }
+        *out = *out - event_old + event;
+
+        return 0;
+    }
     /* TODO datetime64 scalars require conversion
     else if (PyArray_IsScalar(op, Datetime)) {
     }
diff --git a/numpy/core/tests/test_datetime.py b/numpy/core/tests/test_datetime.py
index ddbc8eba2..46fcdc0d9 100644
--- a/numpy/core/tests/test_datetime.py
+++ b/numpy/core/tests/test_datetime.py
@@ -96,6 +96,18 @@ class TestDateTime(TestCase):
                             np.dtype('m8[s]'), np.dtype('m8[as]'))
 
 
+    """
+    def test_pyobject_conversion(self):
+        # All datetime types should be able to roundtrip through object
+        a = np.array([-1020040340, -2942398, -1, 0, 1, 234523453, 1199164176],
+                                                        dtype=np.int64)
+        for unit in ['M8[as]', 'M8[16fs]', 'M8[ps]', 'M8[us]',
+                     'M8[as//12]', 'M8[us//16]', 'M8[D]', 'M8[D]//4',
+                     'M8[W]', 'M8[M]', 'M8[Y]']:
+            assert_equal(a.view(dtype=unit).astype(object).astype(unit),
+                                                        a.view(dtype=unit))
+    """
+
     def test_hours(self):
         t = np.ones(3, dtype='M8[s]')
         t[0] = 60*60*24 + 60*60*10