Merge branch 'update_docs_astype_with_dict_#14761' of https://github.com/m-charlton/pandas into update_docs_astype_with_dict_#14761

Author: m-charlton

doc/source/basics.rst

@@ -1757,12 +1757,14 @@ then the more *general* one will be used as the result of the operation.
    # conversion of dtypes
    df3.astype('float32').dtypes
 
+.. versionadded:: 0.20.0
+
 Convert a subset of columns to a specified type using :meth:`~DataFrame.astype`
 
 .. ipython:: python
 
    dft = pd.DataFrame({'a': [1,2,3], 'b': [4,5,6], 'c': [7, 8, 9]})
-   dft[['a','b']] = dft[['a','b']].astype(np.uint8)
+   dft = dft.astype({'a': np.float64, 'c': np.uint8})
    dft
    dft.dtypes
 

doc/source/whatsnew/v0.20.0.txt

@@ -43,27 +43,15 @@ fixed-width text files, and :func:`read_excel` for parsing Excel files.
    pd.read_fwf(StringIO(data)).dtypes
    pd.read_fwf(StringIO(data), dtype={'a':'float64', 'b':'object'}).dtypes
 
-.. _whatsnew_0200.enhancements.groupby_access:
-
-Groupby Enhancements
-^^^^^^^^^^^^^^^^^^^^
-
-Strings passed to ``DataFrame.groupby()`` as the ``by`` parameter may now reference either column names or index level names (:issue:`5677`)
+You can now pass a dictionary mapping column names to desired data types for that
+column to :meth:`~DataFrame.astype`.
 
 .. ipython:: python
 
-   arrays = [['bar', 'bar', 'baz', 'baz', 'foo', 'foo', 'qux', 'qux'],
-             ['one', 'two', 'one', 'two', 'one', 'two', 'one', 'two']]
-
-   index = pd.MultiIndex.from_arrays(arrays, names=['first', 'second'])
-
-   df = pd.DataFrame({'A': [1, 1, 1, 1, 2, 2, 3, 3],
-                      'B': np.arange(8)},
-                     index=index)
-   df
-
-   df.groupby(['second', 'A']).sum()
-
+   dft = pd.DataFrame({'a': [1,2,3], 'b': [4,5,6], 'c': [7, 8, 9]})
+   dft = dft.astype({'a': np.float64, 'c': np.uint8})
+   dft
+   dft.dtypes
 
 .. _whatsnew_0200.enhancements.other: