BUG: fix loc setitem with a dataframe on rhs, multiple items, and a datetimelike (GH 6152)

Author: jreback

doc/source/release.rst

@@ -165,6 +165,8 @@ Bug Fixes
   - Bug in ``DataFrame.apply`` when using mixed datelike reductions (:issue:`6125`)
   - Bug in ``DataFrame.append`` when appending a row with different columns (:issue:`6129`)
   - Bug in DataFrame construction with recarray and non-ns datetime dtype (:issue:`6140`)
+  - Bug in ``.loc`` setitem indexing with a datafrme on rhs, multiple item setting, and
+    a datetimelike (:issue:`6152`)
 
 pandas 0.13.0
 -------------

pandas/core/common.py

@@ -275,6 +275,10 @@ def notnull(obj):
         return not res
     return -res
 
+def _is_null_datelike_scalar(other):
+    """ test whether the object is a null datelike, e.g. Nat
+    but guard against passing a non-scalar """
+    return (np.isscalar(other) and (isnull(other) or other == tslib.iNaT)) or other is pd.NaT or other is None
 
 def array_equivalent(left, right):
     """

pandas/core/internals.py

@@ -10,7 +10,7 @@
 from pandas.core.common import (_possibly_downcast_to_dtype, isnull, notnull,
                                 _NS_DTYPE, _TD_DTYPE, ABCSeries, is_list_like,
                                 ABCSparseSeries, _infer_dtype_from_scalar,
-                                _values_from_object)
+                                _values_from_object, _is_null_datelike_scalar)
 from pandas.core.index import (Index, MultiIndex, _ensure_index,
                                _handle_legacy_indexes)
 from pandas.core.indexing import (_check_slice_bounds, _maybe_convert_indices,
@@ -1275,7 +1275,7 @@ def masker(v):
 
         values = masker(values)
 
-        if isnull(other) or (np.isscalar(other) and other == tslib.iNaT):
+        if _is_null_datelike_scalar(other):
             other = np.nan
         elif isinstance(other, np.timedelta64):
             other = _coerce_scalar_to_timedelta_type(other, unit='s').item()
@@ -1586,7 +1586,7 @@ def _try_coerce_args(self, values, other):
             we are going to compare vs i8, so coerce to integer
             values is always ndarra like, other may not be """
         values = values.view('i8')
-        if isnull(other) or (np.isscalar(other) and other == tslib.iNaT):
+        if _is_null_datelike_scalar(other):
             other = tslib.iNaT
         elif isinstance(other, datetime):
             other = lib.Timestamp(other).asm8.view('i8')

pandas/tests/test_indexing.py

@@ -646,6 +646,27 @@ def test_loc_setitem_frame(self):
         result = df.ix[:,1:]
         assert_frame_equal(result, expected)
 
+    def test_loc_setitem_frame_multiples(self):
+
+        # multiple setting
+        df = DataFrame({ 'A' : ['foo','bar','baz'],
+                         'B' : range(3) })
+        df.loc[0:1] = df.loc[1:2]
+        expected = DataFrame({ 'A' : ['bar','baz','baz'],
+                               'B' : [1,2,2] })
+        assert_frame_equal(df, expected)
+
+
+        # multiple setting with frame on rhs (with M8)
+        df = DataFrame({ 'date' : date_range('2000-01-01','2000-01-5'),
+                         'val'  : range(5) })
+        expected = DataFrame({ 'date' : [Timestamp('20000101'),Timestamp('20000102'),Timestamp('20000101'),
+                                         Timestamp('20000102'),Timestamp('20000103')],
+                               'val'  : [0,1,0,1,2] })
+
+        df.loc[2:4] = df.loc[0:2]
+        assert_frame_equal(df, expected)
+
     def test_iloc_getitem_frame(self):
         df = DataFrame(np.random.randn(10, 4), index=lrange(0, 20, 2), columns=lrange(0,8,2))