BUG: Check for size != 0 before trying to insert #10193

pandas/core/generic.py

@@ -1286,23 +1286,25 @@ def _check_setitem_copy(self, stacklevel=4, t='setting', force=False):
             elif t == 'referant':
                 t = ("\n"
                      "A value is trying to be set on a copy of a slice from a "
-                     "DataFrame\n\n"
+                     "{name}\n\n"
                      "See the the caveats in the documentation: "
                      "http://pandas.pydata.org/pandas-docs/stable/indexing.html#indexing-view-versus-copy")
 
             else:
                 t = ("\n"
                      "A value is trying to be set on a copy of a slice from a "
-                     "DataFrame.\n"
+                     "{name}.\n"
                      "Try using .loc[row_indexer,col_indexer] = value instead\n\n"
                      "See the the caveats in the documentation: "
                      "http://pandas.pydata.org/pandas-docs/stable/indexing.html#indexing-view-versus-copy")
 
+            t = t.format(name=type(self).__name__)
+
             if value == 'raise':
                 raise SettingWithCopyError(t)
             elif value == 'warn':
                 warnings.warn(t, SettingWithCopyWarning, stacklevel=stacklevel)
-
+        
     def __delitem__(self, key):
         """
         Delete item

pandas/core/series.py

@@ -562,7 +562,10 @@ def _get_with(self, key):
         # other: fancy integer or otherwise
         if isinstance(key, slice):
             indexer = self.index._convert_slice_indexer(key, kind='getitem')
-            return self._get_values(indexer)
+            values = self._get_values(indexer)
+            is_copy = values._is_view
+            values._set_is_copy(self, copy=is_copy)
+            return values
         elif isinstance(key, ABCDataFrame):
             raise TypeError('Indexing a Series with DataFrame is not supported, '\
                             'use the appropriate DataFrame column')
@@ -684,6 +687,7 @@ def setitem(key, value):
         # do the setitem
         cacher_needs_updating = self._check_is_chained_assignment_possible()
         setitem(key, value)
+        self._check_setitem_copy()
         if cacher_needs_updating:
             self._maybe_update_cacher()
 

pandas/tests/test_series.py

@@ -569,7 +569,6 @@ def setUp(self):
 
         self.ts = _ts.copy()
         self.ts.name = 'ts'
-
         self.series = tm.makeStringSeries()
         self.series.name = 'series'
 
@@ -1360,11 +1359,12 @@ def test_slice(self):
 
         self.assertTrue(tm.equalContents(numSliceEnd,
                                          np.array(self.series)[-10:]))
-
-        # test return view
-        sl = self.series[10:20]
-        sl[:] = 0
-        self.assertTrue((self.series[10:20] == 0).all())
+        # After fix for #10193, this is needed
+        with pd.option_context('chained_assignment', 'warn'):
+            # test return view
+            sl = self.series[10:20]
+            sl[:] = 0
+            self.assertTrue((self.series[10:20] == 0).all())
 
     def test_slice_can_reorder_not_uniquely_indexed(self):
         s = Series(1, index=['a', 'a', 'b', 'b', 'c'])
@@ -1439,6 +1439,36 @@ def test_setitem(self):
         expected = self.series.append(Series([1],index=['foobar']))
         assert_series_equal(s,expected)
 
+        # Test for issue #10193
+        key = datetime(2012, 1, 1)
+        series = pd.Series()
+        series[key] = 47
+        expected = pd.Series(47, [key])
+        assert_series_equal(series, expected)
+
+        test_values = [
+            (pd.date_range('2011-01-01', '2011-01-01'), datetime(2012, 1, 1)),
+            (pd.Int64Index([1, 2, 3]), 5)
+        ]
+        for idx, key in test_values:
+
+            series = pd.Series(0, idx)
+            series2 = series[:0]
+
+            def f():
+                series2[key] = 47
+
+            expected = pd.Series(47, [key])
+
+            with pd.option_context('chained_assignment', 'raise'):
+                self.assertRaises(com.SettingWithCopyError, f)
+
+            with pd.option_context('chained_assignment', 'warn'):
+                f()
+                assert_series_equal(series2, expected)
+                # also check that original series remains unchanged.
+                assert_series_equal(series, pd.Series(0, idx))
+
     def test_setitem_dtypes(self):
 
         # change dtypes
@@ -4271,15 +4301,14 @@ def test_underlying_data_conversion(self):
 
         # GH 3970
         # these are chained assignments as well
-        pd.set_option('chained_assignment',None)
-        df = DataFrame({ "aa":range(5), "bb":[2.2]*5})
-        df["cc"] = 0.0
-        ck = [True]*len(df)
-        df["bb"].iloc[0] = .13
-        df_tmp = df.iloc[ck]
-        df["bb"].iloc[0] = .15
-        self.assertEqual(df['bb'].iloc[0], 0.15)
-        pd.set_option('chained_assignment','raise')
+        with pd.option_context('chained_assignment',None):
+            df = DataFrame({ "aa":range(5), "bb":[2.2]*5})
+            df["cc"] = 0.0
+            ck = [True]*len(df)
+            df["bb"].iloc[0] = .13
+            df_tmp = df.iloc[ck]
+            df["bb"].iloc[0] = .15
+            self.assertEqual(df['bb'].iloc[0], 0.15)
 
         # GH 3217
         df = DataFrame(dict(a = [1,3], b = [np.nan, 2]))
@@ -4816,9 +4845,11 @@ def test_rank(self):
         tm._skip_if_no_scipy()
         from scipy.stats import rankdata
 
-        self.ts[::2] = np.nan
-        self.ts[:10][::3] = 4.
-
+        # After fix for #10193, this is needed
+        with pd.option_context('chained_assignment',None):
+            self.ts[::2] = np.nan
+            self.ts[:10][::3] = 4.
+
         ranks = self.ts.rank()
         oranks = self.ts.astype('O').rank()
 

pandas/tseries/index.py

@@ -1521,7 +1521,7 @@ def insert(self, loc, item):
             if zone != izone:
                 raise ValueError('Passed item and index have different timezone')
             # check freq can be preserved on edge cases
-            if self.freq is not None:
+            if self.size and self.freq is not None:
                 if (loc == 0 or loc == -len(self)) and item + self.freq == self[0]:
                     freq = self.freq
                 elif (loc == len(self)) and item - self.freq == self[-1]:

pandas/tseries/tests/test_period.py

@@ -1669,7 +1669,10 @@ def test_index_duplicate_periods(self):
         result = ts[2007]
         expected = ts[1:3]
         assert_series_equal(result, expected)
-        result[:] = 1
+        # After fix for #10193, this is necessary
+        with pd.option_context('chained_assignment',None):
+            result[:] = 1
+
         self.assertTrue((ts[1:3] == 1).all())
 
         # not monotonic