remove need for PandasError sub-class

doc/source/whatsnew/v0.20.0.txt

@@ -877,6 +877,8 @@ Other API Changes
 - ``NaT`` will now correctly return ``np.nan`` for ``Timedelta`` and ``Period`` accessors such as ``days`` and ``quarter`` (:issue:`15782`)
 - ``NaT`` will now returns ``NaT`` for ``tz_localize`` and ``tz_convert``
   methods (:issue:`15830`)
+- ``DataFrame`` and ``Panel`` constructors with invalid input will now raise ``ValueError`` rather than ``PandasError``, if called with scalar inputs and not axes (:issue:`15541`)
+
 
 .. _whatsnew_0200.deprecations:
 

pandas/core/common.py

@@ -22,7 +22,7 @@
 
 # compat
 from pandas.errors import (  # noqa
-    PandasError, PerformanceWarning,
+    PerformanceWarning,
     AmbiguousIndexError, UnsupportedFunctionCall, UnsortedIndexError)
 
 # back-compat of public API

pandas/core/frame.py

@@ -56,7 +56,6 @@
                                  is_named_tuple)
 from pandas.types.missing import isnull, notnull
 
-from pandas.errors import PandasError
 from pandas.core.common import (_try_sort,
                                 _default_index,
                                 _values_from_object,
@@ -348,7 +347,7 @@ def __init__(self, data=None, index=None, columns=None, dtype=None,
                 mgr = self._init_ndarray(values, index, columns, dtype=dtype,
                                          copy=False)
             else:
-                raise PandasError('DataFrame constructor not properly called!')
+                raise ValueError('DataFrame constructor not properly called!')
 
         NDFrame.__init__(self, mgr, fastpath=True)
 

pandas/core/panel.py

@@ -21,7 +21,6 @@
 from pandas import compat
 from pandas.compat import (map, zip, range, u, OrderedDict, OrderedDefaultdict)
 from pandas.compat.numpy import function as nv
-from pandas.errors import PandasError
 from pandas.core.common import _try_sort, _default_index
 from pandas.core.frame import DataFrame
 from pandas.core.generic import NDFrame, _shared_docs
@@ -175,7 +174,7 @@ def _init_data(self, data, copy, dtype, **kwargs):
                                     copy=False)
             copy = False
         else:  # pragma: no cover
-            raise PandasError('Panel constructor not properly called!')
+            raise ValueError('Panel constructor not properly called!')
 
         NDFrame.__init__(self, mgr, axes=axes, copy=copy, dtype=dtype)
 
@@ -1151,8 +1150,8 @@ def _construct_return_type(self, result, axes=None):
             return self._constructor_sliced(
                 result, **self._extract_axes_for_slice(self, axes))
 
-        raise PandasError('invalid _construct_return_type [self->%s] '
-                          '[result->%s]' % (self, result))
+        raise ValueError('invalid _construct_return_type [self->%s] '
+                         '[result->%s]' % (self, result))
 
     def _wrap_result(self, result, axis):
         axis = self._get_axis_name(axis)

pandas/errors/__init__.py

@@ -5,14 +5,10 @@
 from pandas._libs.tslib import OutOfBoundsDatetime
 
 
-class PandasError(Exception):
-    pass
-
-
 class PerformanceWarning(Warning):
     pass
 
-class AmbiguousIndexError(PandasError, KeyError):
+class AmbiguousIndexError(KeyError):
     pass
 
 

pandas/tests/frame/test_constructors.py

@@ -20,7 +20,6 @@
 from pandas import (DataFrame, Index, Series, isnull,
                     MultiIndex, Timedelta, Timestamp,
                     date_range)
-from pandas.errors import PandasError
 import pandas as pd
 import pandas._libs.lib as lib
 import pandas.util.testing as tm
@@ -773,7 +772,7 @@ def test_constructor_more(self):
 
         # corner, silly
         # TODO: Fix this Exception to be better...
-        with tm.assertRaisesRegexp(PandasError, 'constructor not '
+        with tm.assertRaisesRegexp(ValueError, 'constructor not '
                                    'properly called'):
             DataFrame((1, 2, 3))
 
@@ -1241,8 +1240,8 @@ def test_constructor_single_value(self):
                                                      dtype=object),
                                             index=[1, 2], columns=['a', 'c']))
 
-        self.assertRaises(PandasError, DataFrame, 'a', [1, 2])
-        self.assertRaises(PandasError, DataFrame, 'a', columns=['a', 'c'])
+        self.assertRaises(ValueError, DataFrame, 'a', [1, 2])
+        self.assertRaises(ValueError, DataFrame, 'a', columns=['a', 'c'])
         with tm.assertRaisesRegexp(TypeError, 'incompatible data and dtype'):
             DataFrame('a', [1, 2], ['a', 'c'], float)
 

pandas/tests/test_errors.py

@@ -6,7 +6,7 @@
 
 
 @pytest.mark.parametrize(
-    "exc", ['PandasError', 'AmbiguousIndexError',
+    "exc", ['AmbiguousIndexError',
             'UnsupportedFunctionCall', 'UnsortedIndexError',
             'OutOfBoundsDatetime',
             'ParserError', 'PerformanceWarning', 'DtypeWarning',

pandas/tseries/index.py

@@ -618,8 +618,7 @@ def _has_same_tz(self, other):
     def _cached_range(cls, start=None, end=None, periods=None, offset=None,
                       name=None):
         if start is None and end is None:
-            # I somewhat believe this should never be raised externally and
-            # therefore should be a `PandasError` but whatever...
+            # I somewhat believe this should never be raised externally
             raise TypeError('Must specify either start or end.')
         if start is not None:
             start = Timestamp(start)
@@ -630,8 +629,7 @@ def _cached_range(cls, start=None, end=None, periods=None, offset=None,
                 'Must either specify period or provide both start and end.')
 
         if offset is None:
-            # This can't happen with external-facing code, therefore
-            # PandasError
+            # This can't happen with external-facing code
             raise TypeError('Must provide offset.')
 
         drc = _daterange_cache