make _is_view more conservative on multi-block objects

tweak so addition of new columnsdoesn't cause copying improved tests, removed copy option from merge

pandas/core/frame.py

@@ -4370,12 +4370,12 @@ def _join_compat(self, other, on=None, how='left', lsuffix='', rsuffix='',
  @Appender(_merge_doc, indents=2)
  def merge(self, right, how='inner', on=None, left_on=None, right_on=None,
  left_index=False, right_index=False, sort=False,
- suffixes=('_x', '_y'), copy=True, indicator=False):
+ suffixes=('_x', '_y'), indicator=False):
  from pandas.tools.merge import merge
  return merge(self, right, how=how, on=on,
  left_on=left_on, right_on=right_on,
  left_index=left_index, right_index=right_index, sort=sort,
- suffixes=suffixes, copy=copy, indicator=indicator)
+ suffixes=suffixes, indicator=indicator)
 
  def round(self, decimals=0, out=None):
  """

pandas/core/generic.py

@@ -1091,9 +1091,6 @@ def get(self, key, default=None):
  def __getitem__(self, item):
  result = self._get_item_cache(item)
 
- if isinstance(item, str):
- result._is_column_view = True 
-
  return result
 
  def _get_item_cache(self, item):
@@ -1218,10 +1215,14 @@ def _slice(self, slobj, axis=0, kind=None):
  return result
 
  def _set_item(self, key, value):
-
- # If children are views, reset to copies before setting.
- self._execute_copy_on_write()
 
+ if hasattr(self, 'columns'):
+ if key in self.columns:
+ # If children are views, reset to copies before setting.
+ self._execute_copy_on_write()
+ else: 
+ self._execute_copy_on_write()
+
  self._data.set(key, value)
  self._clear_item_cache()
 
@@ -2339,6 +2340,9 @@ def __setattr__(self, name, value):
  # e.g. ``obj.x`` and ``obj.x = 4`` will always reference/modify
  # the same attribute.
 
+ if hasattr(self, 'columns'):
+ if name in self.columns:
+ self._execute_copy_on_write()
 
  try:
  object.__getattribute__(self, name)

pandas/core/internals.py

@@ -2933,10 +2933,11 @@ def is_datelike_mixed_type(self):
 
  @property
  def is_view(self):
- """ return a boolean if we are a single block and are a view """
- if len(self.blocks) == 1:
- return self.blocks[0].is_view
-
+ """ return a boolean True if any block is a view """
+ for b in self.blocks:
+ if b.is_view: return True
+
+
  # It is technically possible to figure out which blocks are views
  # e.g. [ b.values.base is not None for b in self.blocks ]
  # but then we have the case of possibly some blocks being a view

pandas/core/panel.py

@@ -1339,8 +1339,10 @@ def update(self, other, join='left', overwrite=True, filter_func=None,
  other = other.reindex(**{axis_name: axis_values})
 
  for frame in axis_values:
- self[frame].update(other[frame], join, overwrite, filter_func,
+ temp = self[frame]
+ temp.update(other[frame], join, overwrite, filter_func,
  raise_conflict)
+ self[frame] = temp
 
  def _get_join_index(self, other, how):
  if how == 'left':

pandas/core/reshape.py

@@ -945,7 +945,7 @@ def melt_stub(df, stub, i, j):
 
  for stub in stubnames[1:]:
  new = melt_stub(df, stub, id_vars, j)
- newdf = newdf.merge(new, how="outer", on=id_vars + [j], copy=False)
+ newdf = newdf.merge(new, how="outer", on=id_vars + [j])
  return newdf.set_index([i, j])
 
 def get_dummies(data, prefix=None, prefix_sep='_', dummy_na=False,

pandas/tests/test_frame.py

@@ -194,7 +194,6 @@ def test_setitem_list(self):
 
  assert_series_equal(self.frame['B'], data['A'], check_names=False)
  assert_series_equal(self.frame['A'], data['B'], check_names=False)
-
  with assertRaisesRegexp(ValueError, 'Columns must be same length as key'):
  data[['A']] = self.frame[['A', 'B']]
  with assertRaisesRegexp(ValueError, 'Length of values does not match '
@@ -561,14 +560,14 @@ def test_setitem(self):
  self.frame['col8'] = 'foo'
  assert((self.frame['col8'] == 'foo').all())
 
- # this is partially a view (e.g. some blocks are view)
- # so raise/warn
+ # Changes should not propageate
  smaller = self.frame[:2]
  def f():
- smaller['col10'] = ['1', '2']
- self.assertRaises(com.SettingWithCopyError, f)
- self.assertEqual(smaller['col10'].dtype, np.object_)
- self.assertTrue((smaller['col10'] == ['1', '2']).all())
+ smaller['col0'] = ['1', '2']
+ f()
+ self.assertEqual(smaller['col0'].dtype, np.object_)
+ self.assertTrue((smaller['col0'] == ['1', '2']).all())
+ self.assertNotEqual(self.frame[:2].col0.dtype, np.object_)
 
  # with a dtype
  for dtype in ['int32','int64','float32','float64']:
@@ -1022,13 +1021,11 @@ def test_fancy_getitem_slice_mixed(self):
  sliced = self.mixed_frame.ix[:, -3:]
  self.assertEqual(sliced['D'].dtype, np.float64)
 
- # get view with single block
- # setting it triggers setting with copy
+ # Should never act as view due to copy on write
  sliced = self.frame.ix[:, -3:]
  def f():
- sliced['C'] = 4.
- self.assertRaises(com.SettingWithCopyError, f)
- self.assertTrue((self.frame['C'] == 4).all())
+ sliced['C'] = 4
+ self.assertTrue((self.frame['C'] != 4).all())
 
  def test_fancy_setitem_int_labels(self):
  # integer index defers to label-based indexing
@@ -1827,14 +1824,12 @@ def test_irow(self):
  expected = df.ix[8:14]
  assert_frame_equal(result, expected)
 
- # verify slice is view
- # setting it makes it raise/warn
+ # verify changes on slices never propogate
  def f():
  result[2] = 0.
- self.assertRaises(com.SettingWithCopyError, f)
  exp_col = df[2].copy()
  exp_col[4:8] = 0.
- assert_series_equal(df[2], exp_col)
+ self.assertFalse((df[2] == exp_col).all())
 
  # list of integers
  result = df.iloc[[1, 2, 4, 6]]
@@ -1862,12 +1857,10 @@ def test_icol(self):
  expected = df.ix[:, 8:14]
  assert_frame_equal(result, expected)
 
- # verify slice is view
- # and that we are setting a copy
+ # Verify setting on view doesn't propogate
  def f():
  result[8] = 0.
- self.assertRaises(com.SettingWithCopyError, f)
- self.assertTrue((df[8] == 0).all())
+ self.assertTrue((df[8] != 0).all())
 
  # list of integers
  result = df.iloc[:, [1, 2, 4, 6]]
@@ -4343,12 +4336,6 @@ def test_constructor_with_datetime_tz(self):
  assert_series_equal(df['D'],Series(idx,name='D'))
  del df['D']
 
- # assert that A & C are not sharing the same base (e.g. they
- # are copies)
- b1 = df._data.blocks[1]
- b2 = df._data.blocks[2]
- self.assertTrue(b1.values.equals(b2.values))
- self.assertFalse(id(b1.values.values.base) == id(b2.values.values.base))
 
  # with nan
  df2 = df.copy()

pandas/tests/test_generic.py

@@ -1740,7 +1740,6 @@ def test_copy_on_write(self):
  copies[v] = views[v].copy()
 
 
-
  df.loc[0,'col1'] = -88
 
  for v in views.keys():
@@ -1807,6 +1806,23 @@ def test_copy_on_write(self):
  df.loc[0, 'col1']=-88
  self.assertTrue(v.loc[0] == -88)
  self.assertTrue(v._is_view)
+
+ # Does NOT hold for multi-index (can't guarantee view behaviors --
+ # setting on multi-index creates new data somehow.)
+ index = pd.MultiIndex(levels=[['foo', 'bar', 'baz', 'qux'],
+ ['one', 'two', 'three']],
+ labels=[[0, 0, 0, 1, 1, 2, 2, 3, 3, 3],
+ [0, 1, 2, 0, 1, 1, 2, 0, 1, 2]],
+ names=['first', 'second'])
+ frame = pd.DataFrame(np.random.randn(10, 3), index=index,
+ columns=pd.Index(['A', 'B', 'C'], name='exp')).T
+
+ v = frame['foo','one']
+ self.assertTrue(v._is_view)
+ self.assertFalse(v._is_column_view)
+ frame.loc['A', ('foo','one')]=-88
+ self.assertFalse(v.loc['A'] == -88)
+
 
  ###
  # Make sure that no problems if view created on view and middle-view
@@ -1827,7 +1843,14 @@ def test_copy_on_write(self):
  tm.assert_frame_equal(v2, v2_copy)
 
 
-
+ def test_is_view_of_multiblocks(self):
+ # Ensure that if even if only one block of DF is view, 
+ # returns _is_view = True. 
+ df = pd.DataFrame({'col1':[1,2], 'col2':[3,4]})
+ s = pd.Series([0.5, 0.3, 0.4])
+ df['col3'] = s[0:1]
+ self.assertTrue(df['col3']._is_view) 
+ self.assertTrue(df._is_view)
 
 class TestPanel(tm.TestCase, Generic):
  _typ = Panel