DOC: Fix validation error RT01 in pandas/core (pandas-dev#25356)

Except errors in accessor.py, op.py and some errors in resample.py, frame.py

Author: ihsansecer

pandas/core/base.py

@@ -656,6 +656,10 @@ class IndexOpsMixin:
     def transpose(self, *args, **kwargs):
         """
         Return the transpose, which is by definition self.
+
+        Returns
+        -------
+        self: %(klass)s
         """
         nv.validate_transpose(args, kwargs)
         return self
@@ -696,6 +700,11 @@ def ndim(self):
     def item(self):
         """
         Return the first element of the underlying data as a python scalar.
+
+        Returns
+        -------
+        scalar
+            The first element of %(klass)s.
         """
         return self.values.item()
 
@@ -1016,6 +1025,11 @@ def argmax(self, axis=None, skipna=True):
             Dummy argument for consistency with Series
         skipna : bool, default True
 
+        Returns
+        -------
+        numpy.ndarray
+            Indices of the maximum values.
+
         See Also
         --------
         numpy.ndarray.argmax
@@ -1116,6 +1130,10 @@ def __iter__(self):
         These are each a scalar type, which is a Python scalar
         (for str, int, float) or a pandas scalar
         (for Timestamp/Timedelta/Interval/Period)
+
+        Returns
+        -------
+        iterator
         """
         # We are explicity making element iterators.
         if is_datetimelike(self._values):

pandas/core/frame.py

@@ -1388,6 +1388,10 @@ def to_gbq(self, destination_table, project_id=None, chunksize=None,
             or string contents. This is useful for remote server
             authentication (eg. Jupyter/IPython notebook on remote host).
 
+        Returns
+        -------
+        None
+
         See Also
         --------
         pandas_gbq.to_gbq : This function in the pandas-gbq library.
@@ -3663,6 +3667,11 @@ def lookup(self, row_labels, col_labels):
         col_labels : sequence
             The column labels to use for lookup
 
+        Returns
+        -------
+        numpy.ndarray
+            Array of the values corresponding to each (row, col) pair.
+
         Notes
         -----
         Akin to::
@@ -6051,6 +6060,11 @@ def unstack(self, level=-1, fill_value=None):
     col_level : int or string, optional
         If columns are a MultiIndex then use this level to melt.
 
+    Returns
+    -------
+    DataFrame
+        Unpivoted DataFrame.
+
     See Also
     --------
     %(other)s

pandas/core/generic.py

@@ -1518,6 +1518,11 @@ def bool(self):
         This must be a boolean scalar value, either True or False.  Raise a
         ValueError if the PandasObject does not have exactly 1 element, or that
         element is not boolean
+
+        Returns
+        -------
+        boolean
+            Same single boolean value converted to bool type.
         """
         v = self.squeeze()
         if isinstance(v, (bool, np.bool_)):
@@ -1845,7 +1850,13 @@ def __hash__(self):
                         ' hashed'.format(self.__class__.__name__))
 
     def __iter__(self):
-        """Iterate over info axis"""
+        """Iterate over info axis
+        
+        Returns
+        -------
+        iterator
+            Info axis as iterator.
+        """
         return iter(self._info_axis)
 
     # can we get a better explanation of this?
@@ -1854,6 +1865,11 @@ def keys(self):
 
         This is index for Series, columns for DataFrame and major_axis for
         Panel.
+
+        Returns
+        -------
+        Index
+            Info axis.
         """
         return self._info_axis
 
@@ -1948,6 +1964,11 @@ def __array_wrap__(self, result, context=None):
     def to_dense(self):
         """
         Return dense representation of NDFrame (as opposed to sparse).
+
+        Returns
+        -------
+        self: %(klass)s
+            Dense %(klass)s.
         """
         # compat
         return self
@@ -2240,6 +2261,12 @@ def to_json(self, path_or_buf=None, orient=None, date_format=None,
 
             .. versionadded:: 0.23.0
 
+        Returns
+        -------
+        None or str
+            If path_or_buf is None, returns the resulting json format as a
+            string. Otherwise returns None.
+
         See Also
         --------
         read_json
@@ -2364,6 +2391,10 @@ def to_hdf(self, path_or_buf, key, **kwargs):
             See the errors argument for :func:`open` for a full list
             of options.
 
+        Returns
+        -------
+        None
+
         See Also
         --------
         DataFrame.read_hdf : Read from HDF file.
@@ -2420,6 +2451,12 @@ def to_msgpack(self, path_or_buf=None, encoding='utf-8', **kwargs):
             (default is False)
         compress : type of compressor (zlib or blosc), default to None (no
             compression)
+
+        Returns
+        -------
+        None or str
+            If path_or_buf is None, returns the resulting msgpack format as a
+            string. Otherwise returns None.
         """
 
         from pandas.io import packers
@@ -2583,6 +2620,10 @@ def to_pickle(self, path, compression='infer',
             .. [1] https://docs.python.org/3/library/pickle.html
             .. versionadded:: 0.21.0
 
+        Returns
+        -------
+        None
+
         See Also
         --------
         read_pickle : Load pickled pandas object (or any object) from file.
@@ -6171,13 +6212,23 @@ def fillna(self, value=None, method=None, axis=None, inplace=False,
     def ffill(self, axis=None, inplace=False, limit=None, downcast=None):
         """
         Synonym for :meth:`DataFrame.fillna` with ``method='ffill'``.
+
+        Returns
+        -------
+        %(klass)s
+            Object with missing values filled.
         """
         return self.fillna(method='ffill', axis=axis, inplace=inplace,
                            limit=limit, downcast=downcast)
 
     def bfill(self, axis=None, inplace=False, limit=None, downcast=None):
         """
         Synonym for :meth:`DataFrame.fillna` with ``method='bfill'``.
+
+        Returns
+        -------
+        %(klass)s
+            Object with missing values filled.
         """
         return self.fillna(method='bfill', axis=axis, inplace=inplace,
                            limit=limit, downcast=downcast)
@@ -9270,6 +9321,8 @@ def tz_convert(self, tz, axis=0, level=None, copy=True):
 
         Returns
         -------
+        %(klass)s
+            %(klass)s with time zone converted axis.
 
         Raises
         ------

pandas/core/resample.py

@@ -780,6 +780,11 @@ def asfreq(self, fill_value=None):
 
             .. versionadded:: 0.20.0
 
+        Returns
+        -------
+        DataFrame or Series
+            Values at the specified freq.
+
         See Also
         --------
         Series.asfreq
@@ -795,6 +800,11 @@ def std(self, ddof=1, *args, **kwargs):
         ----------
         ddof : integer, default 1
             Degrees of freedom.
+
+        Returns
+        -------
+        DataFrame or Series
+            Standard deviation of values within each group.
         """
         nv.validate_resampler_func('std', args, kwargs)
         return self._downsample('std', ddof=ddof)
@@ -807,12 +817,23 @@ def var(self, ddof=1, *args, **kwargs):
         ----------
         ddof : integer, default 1
             degrees of freedom
+
+        Returns
+        -------
+        DataFrame or Series
+            Variance of values within each group.
         """
         nv.validate_resampler_func('var', args, kwargs)
         return self._downsample('var', ddof=ddof)
 
     @Appender(GroupBy.size.__doc__)
     def size(self):
+        """
+        Returns
+        -------
+        Series
+            Number of rows in each group.
+        """
         # It's a special case as higher level does return
         # a copy of 0-len objects. GH14962
         result = self._downsample('size')
@@ -830,6 +851,11 @@ def quantile(self, q=0.5, **kwargs):
         ----------
         q : float or array-like, default 0.5 (50% quantile)
 
+        Returns
+        -------
+        DataFrame or Series
+            Quantile of values within each group.
+
         See Also
         --------
         Series.quantile

pandas/core/series.py

@@ -319,6 +319,11 @@ def from_array(cls, arr, index=None, name=None, dtype=None, copy=False,
 
         .. deprecated :: 0.23.0
             Use pd.Series(..) constructor instead.
+
+        Returns
+        -------
+        Series
+            Constructed Series.
         """
         warnings.warn("'from_array' is deprecated and will be removed in a "
                       "future version. Please use the pd.Series(..) "
@@ -486,6 +491,11 @@ def _formatting_values(self):
     def get_values(self):
         """
         Same as values (but handles sparseness conversions); is a view.
+
+        Returns
+        -------
+        numpy.ndarray
+            Data of the Series.
         """
         return self._data.get_values()
 
@@ -526,6 +536,11 @@ def compress(self, condition, *args, **kwargs):
 
         .. deprecated:: 0.24.0
 
+        Returns
+        -------
+        Series
+            Series without the slices for which condition is false.
+
         See Also
         --------
         numpy.ndarray.compress
@@ -550,6 +565,11 @@ def nonzero(self):
         but it will always be a one-item tuple because series only have
         one dimension.
 
+        Returns
+        -------
+        numpy.ndarray
+            Indices of elements that are non-zero.
+
         See Also
         --------
         numpy.nonzero
@@ -1479,6 +1499,11 @@ def iteritems(self):
     def keys(self):
         """
         Return alias for index.
+
+        Returns
+        -------
+        Index
+            Index of the Series.
         """
         return self.index
 
@@ -3943,6 +3968,11 @@ def reindex_axis(self, labels, axis=0, **kwargs):
 
         .. deprecated:: 0.21.0
             Use ``Series.reindex`` instead.
+
+        Returns
+        -------
+        Series
+            Reindexed Series.
         """
         # for compatibility with higher dims
         if axis != 0:
@@ -4406,6 +4436,11 @@ def valid(self, inplace=False, **kwargs):
 
         .. deprecated:: 0.23.0
             Use :meth:`Series.dropna` instead.
+
+        Returns
+        -------
+        Series
+            Series without null values.
         """
         warnings.warn("Method .valid will be removed in a future version. "
                       "Use .dropna instead.", FutureWarning, stacklevel=2)