Revert "MAINT: Remove Long and WidePanel (#15748)" (#15802)

This reverts commit bff47f2.

asv_bench/benchmarks/pandas_vb_common.py

@@ -25,6 +25,11 @@
     except:
         pass
 
+try:
+    Panel = Panel
+except Exception:
+    Panel = WidePanel
+
 # didn't add to namespace until later
 try:
     from pandas.core.index import MultiIndex

bench/bench_join_panel.py

@@ -45,8 +45,8 @@ def reindex_on_axis(panels, axis, axis_reindex):
         return p
 
 
-# Does the job but inefficient. It is better to handle
-# this like you read a table in pytables.
+# does the job but inefficient (better to handle like you read a table in
+# pytables...e.g create a LongPanel then convert to Wide)
 def create_panels_join(cls, panels):
         """ given an array of panels's, create a single panel """
         panels = [a for a in panels if a is not None]

doc/source/whatsnew/v0.20.0.txt

@@ -814,7 +814,6 @@ Removal of prior version deprecations/changes
 - The ``take_last`` parameter has been dropped from ``duplicated()``, ``drop_duplicates()``, ``nlargest()``, and ``nsmallest()`` methods (:issue:`10236`, :issue:`10792`, :issue:`10920`)
 - ``Series``, ``Index``, and ``DataFrame`` have dropped the ``sort`` and ``order`` methods (:issue:`10726`)
 - Where clauses in ``pytables`` are only accepted as strings and expressions types and not other data-types (:issue:`12027`)
-- The ``LongPanel`` and ``WidePanel`` classes have been removed (:issue:`10892`)
 
 .. _whatsnew_0200.performance:
 

pandas/core/api.py

@@ -15,7 +15,7 @@
 
 from pandas.core.series import Series
 from pandas.core.frame import DataFrame
-from pandas.core.panel import Panel
+from pandas.core.panel import Panel, WidePanel
 from pandas.core.panel4d import Panel4D
 from pandas.core.reshape import (pivot_simple as pivot, get_dummies,
                                  lreshape, wide_to_long)

pandas/core/panel.py

@@ -4,6 +4,8 @@
 # pylint: disable=E1103,W0231,W0212,W0621
 from __future__ import division
 
+import warnings
+
 import numpy as np
 
 from pandas.types.cast import (infer_dtype_from_scalar,
@@ -1554,3 +1556,24 @@ def f(self, other, axis=0):
 ops.add_special_arithmetic_methods(Panel, **ops.panel_special_funcs)
 Panel._add_aggregate_operations()
 Panel._add_numeric_operations()
+
+
+# legacy
+class WidePanel(Panel):
+
+    def __init__(self, *args, **kwargs):
+        # deprecation, #10892
+        warnings.warn("WidePanel is deprecated. Please use Panel",
+                      FutureWarning, stacklevel=2)
+
+        super(WidePanel, self).__init__(*args, **kwargs)
+
+
+class LongPanel(DataFrame):
+
+    def __init__(self, *args, **kwargs):
+        # deprecation, #10892
+        warnings.warn("LongPanel is deprecated. Please use DataFrame",
+                      FutureWarning, stacklevel=2)
+
+        super(LongPanel, self).__init__(*args, **kwargs)

pandas/tests/api/test_api.py

@@ -54,7 +54,8 @@ class TestPDApi(Base, tm.TestCase):
                'TimedeltaIndex', 'Timestamp']
 
     # these are already deprecated; awaiting removal
-    deprecated_classes = ['Panel4D', 'SparseList', 'Expr', 'Term']
+    deprecated_classes = ['WidePanel', 'Panel4D',
+                          'SparseList', 'Expr', 'Term']
 
     # these should be deprecated in the future
     deprecated_classes_in_future = ['Panel']

pandas/tests/io/test_pytables.py

@@ -2964,6 +2964,9 @@ def _check(left, right):
         # empty
         # self._check_roundtrip(wp.to_frame()[:0], _check)
 
+    def test_longpanel(self):
+        pass
+
     def test_overwrite_node(self):
 
         with ensure_clean_store(self.path) as store:

pandas/tests/test_panel.py

@@ -178,6 +178,10 @@ def wrapper(x):
 
 class SafeForSparse(object):
 
+    @classmethod
+    def assert_panel_equal(cls, x, y):
+        assert_panel_equal(x, y)
+
     def test_get_axis(self):
         assert (self.panel._get_axis(0) is self.panel.items)
         assert (self.panel._get_axis(1) is self.panel.major_axis)
@@ -342,10 +346,10 @@ def check_op(op, name):
 
     def test_combinePanel(self):
         result = self.panel.add(self.panel)
-        assert_panel_equal(result, self.panel * 2)
+        self.assert_panel_equal(result, self.panel * 2)
 
     def test_neg(self):
-        assert_panel_equal(-self.panel, self.panel * -1)
+        self.assert_panel_equal(-self.panel, self.panel * -1)
 
     # issue 7692
     def test_raise_when_not_implemented(self):
@@ -365,22 +369,22 @@ def test_select(self):
         # select items
         result = p.select(lambda x: x in ('ItemA', 'ItemC'), axis='items')
         expected = p.reindex(items=['ItemA', 'ItemC'])
-        assert_panel_equal(result, expected)
+        self.assert_panel_equal(result, expected)
 
         # select major_axis
         result = p.select(lambda x: x >= datetime(2000, 1, 15), axis='major')
         new_major = p.major_axis[p.major_axis >= datetime(2000, 1, 15)]
         expected = p.reindex(major=new_major)
-        assert_panel_equal(result, expected)
+        self.assert_panel_equal(result, expected)
 
         # select minor_axis
         result = p.select(lambda x: x in ('D', 'A'), axis=2)
         expected = p.reindex(minor=['A', 'D'])
-        assert_panel_equal(result, expected)
+        self.assert_panel_equal(result, expected)
 
         # corner case, empty thing
         result = p.select(lambda x: x in ('foo', ), axis='items')
-        assert_panel_equal(result, p.reindex(items=[]))
+        self.assert_panel_equal(result, p.reindex(items=[]))
 
     def test_get_value(self):
         for item in self.panel.items:
@@ -395,8 +399,8 @@ def test_abs(self):
         result = self.panel.abs()
         result2 = abs(self.panel)
         expected = np.abs(self.panel)
-        assert_panel_equal(result, expected)
-        assert_panel_equal(result2, expected)
+        self.assert_panel_equal(result, expected)
+        self.assert_panel_equal(result2, expected)
 
         df = self.panel['ItemA']
         result = df.abs()
@@ -863,6 +867,10 @@ def test_set_value(self):
 class TestPanel(tm.TestCase, PanelTests, CheckIndexing, SafeForLongAndSparse,
                 SafeForSparse):
 
+    @classmethod
+    def assert_panel_equal(cls, x, y):
+        assert_panel_equal(x, y)
+
     def setUp(self):
         self.panel = _panel.copy()
         self.panel.major_axis.name = None
@@ -1959,7 +1967,7 @@ def test_round(self):
                          major_axis=pd.date_range('1/1/2000', periods=5),
                          minor_axis=['A', 'B'])
         result = p.round()
-        assert_panel_equal(expected, result)
+        self.assert_panel_equal(expected, result)
 
     def test_numpy_round(self):
         values = [[[-3.2, 2.2], [0, -4.8213], [3.123, 123.12],
@@ -1975,7 +1983,7 @@ def test_numpy_round(self):
                          major_axis=pd.date_range('1/1/2000', periods=5),
                          minor_axis=['A', 'B'])
         result = np.round(p)
-        assert_panel_equal(expected, result)
+        self.assert_panel_equal(expected, result)
 
         msg = "the 'out' parameter is not supported"
         tm.assertRaisesRegexp(ValueError, msg, np.round, p, out=p)
@@ -2262,12 +2270,15 @@ def test_all_any_unhandled(self):
         self.assertRaises(NotImplementedError, self.panel.any, bool_only=True)
 
 
-class TestPanelFrame(tm.TestCase):
+class TestLongPanel(tm.TestCase):
     """
-    Check that conversions to and from Panel to DataFrame work.
+    LongPanel no longer exists, but...
     """
 
     def setUp(self):
+        import warnings
+        warnings.filterwarnings(action='ignore', category=FutureWarning)
+
         panel = tm.makePanel()
         tm.add_nans(panel)
 

vb_suite/pandas_vb_common.py

@@ -18,6 +18,11 @@
 except:
     import pandas._libs.lib as lib
 
+try:
+    Panel = WidePanel
+except Exception:
+    pass
+
 # didn't add to namespace until later
 try:
     from pandas.core.index import MultiIndex