Merge remote branch 'jreback/maskv3'

* jreback/maskv3:
  added back mask method that does condition inversion added condition testing to where that raised ValueError on an invalid condition (e.g. not an ndarray like object) added tests for same
  in core/frame.py
  fixed file modes for core/frame.py, test/test_frame.py
  relaxed __setitem__ restriction on boolean indexing a frame on an equal sized frame
  in core/frame.py

Author: wesm

pandas/core/frame.py

@@ -1775,9 +1775,8 @@ def __getitem__(self, key):
         elif isinstance(self.columns, MultiIndex):
             return self._getitem_multilevel(key)
         elif isinstance(key, DataFrame):
-            values = key.values
-            if values.dtype == bool:
-                return self.values[values]
+            if key.values.dtype == bool:
+                return self.where(key)
             else:
                 raise ValueError('Cannot index using non-boolean DataFrame')
         else:
@@ -1871,11 +1870,6 @@ def __setitem__(self, key, value):
         # support boolean setting with DataFrame input, e.g.
         # df[df > df2] = 0
         if isinstance(key, DataFrame):
-            if not (key.index.equals(self.index) and
-                    key.columns.equals(self.columns)):
-                raise PandasError('Can only index with like-indexed '
-                                  'DataFrame objects')
-
             self._boolean_set(key, value)
         elif isinstance(key, (np.ndarray, list)):
             return self._set_item_multiple(key, value)
@@ -1884,18 +1878,13 @@ def __setitem__(self, key, value):
             self._set_item(key, value)
 
     def _boolean_set(self, key, value):
-        mask = key.values
-        if mask.dtype != np.bool_:
+        if key.values.dtype != np.bool_:
             raise ValueError('Must pass DataFrame with boolean values only')
 
         if self._is_mixed_type:
             raise ValueError('Cannot do boolean setting on mixed-type frame')
 
-        if isinstance(value, DataFrame):
-            assert(value._indexed_same(self))
-            np.putmask(self.values, mask, value.values)
-        else:
-            self.values[mask] = value
+        self.where(key, value, inplace=True)
 
     def _set_item_multiple(self, keys, value):
         if isinstance(value, DataFrame):
@@ -4878,7 +4867,7 @@ def combineMult(self, other):
         """
         return self.mul(other, fill_value=1.)
 
-    def where(self, cond, other):
+    def where(self, cond, other=NA, inplace=False):
         """
         Return a DataFrame with the same shape as self and whose corresponding
         entries are from self where cond is True and otherwise are from other.
@@ -4893,6 +4882,9 @@ def where(self, cond, other):
         -------
         wh: DataFrame
         """
+        if not hasattr(cond,'shape'):
+            raise ValueError('where requires an ndarray like object for its condition')
+
         if isinstance(cond, np.ndarray):
             if cond.shape != self.shape:
                 raise ValueError('Array onditional must be same shape as self')
@@ -4905,13 +4897,17 @@ def where(self, cond, other):
         if isinstance(other, DataFrame):
             _, other = self.align(other, join='left', fill_value=NA)
 
+        if inplace:
+            np.putmask(self.values, cond, other)
+            return self
+
         rs = np.where(cond, self, other)
         return self._constructor(rs, self.index, self.columns)
-
+        
     def mask(self, cond):
         """
         Returns copy of self whose values are replaced with nan if the
-        corresponding entry in cond is False
+        inverted condition is True
 
         Parameters
         ----------
@@ -4921,7 +4917,7 @@ def mask(self, cond):
         -------
         wh: DataFrame
         """
-        return self.where(cond, NA)
+        return self.where(~cond, NA)
 
 _EMPTY_SERIES = Series([])
 

pandas/tests/test_frame.py

@@ -141,6 +141,12 @@ def test_getitem_boolean(self):
 
         self.assertRaises(ValueError, self.tsframe.__getitem__, self.tsframe)
 
+        # test df[df >0] works
+        bif = self.tsframe[self.tsframe > 0]
+        bifw = DataFrame(np.where(self.tsframe>0,self.tsframe,np.nan),index=self.tsframe.index,columns=self.tsframe.columns)
+        self.assert_(isinstance(bif,DataFrame))
+        self.assert_(bif.shape == self.tsframe.shape)
+        assert_frame_equal(bif,bifw)
 
     def test_getitem_boolean_list(self):
         df = DataFrame(np.arange(12).reshape(3,4))
@@ -278,7 +284,11 @@ def test_setitem_boolean(self):
         values[values == 5] = 0
         assert_almost_equal(df.values, values)
 
-        self.assertRaises(Exception, df.__setitem__, df[:-1] > 0, 2)
+        # a df that needs alignment first
+        df[df[:-1]<0] = 2
+        np.putmask(values[:-1],values[:-1]<0,2)
+        assert_almost_equal(df.values, values)
+
         self.assertRaises(Exception, df.__setitem__, df * 0, 2)
 
         # index with DataFrame
@@ -5248,14 +5258,24 @@ def test_where(self):
         for k, v in rs.iteritems():
             assert_series_equal(v, np.where(cond[k], df[k], other5))
 
-        assert_frame_equal(rs, df.mask(cond))
-
         err1 = (df + 1).values[0:2, :]
         self.assertRaises(ValueError, df.where, cond, err1)
 
         err2 = cond.ix[:2, :].values
         self.assertRaises(ValueError, df.where, err2, other1)
 
+        # invalid conditions
+        self.assertRaises(ValueError, df.mask, True)
+        self.assertRaises(ValueError, df.mask, 0)
+
+    def test_mask(self):
+        df = DataFrame(np.random.randn(5, 3))
+        cond = df > 0
+
+        rs = df.where(cond, np.nan)
+        assert_frame_equal(rs, df.mask(df <= 0))
+        assert_frame_equal(rs, df.mask(~cond))
+
 
     #----------------------------------------------------------------------
     # Transposing