MAINT: Remove Long and WidePanel

Deprecated since 0.17.0.

xref pandas-devgh-10892

Author: gfyoung

bench/bench_join_panel.py

@@ -45,8 +45,8 @@ def reindex_on_axis(panels, axis, axis_reindex):
         return p
 
 
-# does the job but inefficient (better to handle like you read a table in
-# pytables...e.g create a LongPanel then convert to Wide)
+# Does the job but inefficient. It is better to handle
+# this like you read a table in pytables.
 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

@@ -772,6 +772,7 @@ Removal of prior version deprecations/changes
 - The ``Categorical`` constructor has dropped the ``name`` parameter (:issue:`10632`)
 - 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`)
+- The ``LongPanel`` and ``WidePanel`` classes have been removed (:issue:`10892`)
 
 .. _whatsnew_0200.performance: