Use pprint_thing in IndexGroupByGroups. Add whatsnew, docstring, and a couple typo fixes

Author: benjaminarjun

doc/source/whatsnew/v0.25.0.rst

@@ -87,7 +87,8 @@ Other API Changes
 - :class:`DatetimeTZDtype` will now standardize pytz timezones to a common timezone instance (:issue:`24713`)
 - ``Timestamp`` and ``Timedelta`` scalars now implement the :meth:`to_numpy` method as aliases to :meth:`Timestamp.to_datetime64` and :meth:`Timedelta.to_timedelta64`, respectively. (:issue:`24653`)
 - :meth:`Timestamp.strptime` will now rise a ``NotImplementedError`` (:issue:`25016`)
-- Bug in :meth:`DatetimeIndex.snap` which didn't preserving the ``name`` of the input :class:`Index` (:issue:`25575`)
+- Bug in :meth:`DatetimeIndex.snap` which didn't preserve the ``name`` of the input :class:`Index` (:issue:`25575`)
+- :meth:`Index.groupby` and dependent methods (notably :meth:`GroupBy.groups`) now return object with abbreviated repr (:issue:`1135`)
 
 .. _whatsnew_0250.deprecations:
 

pandas/core/groupby/groupby.py

@@ -54,7 +54,7 @@ class providing the base-class of operations.
 
 _apply_docs = dict(
     template="""
-    Apply function `func`  group-wise and combine the results together.
+    Apply function `func` group-wise and combine the results together.
 
     The function passed to `apply` must take a {input} as its first
     argument and return a DataFrame, Series or scalar. `apply` will

pandas/core/indexes/base.py

@@ -5291,24 +5291,11 @@ def _add_logical_methods_disabled(cls):
 
 
 class IndexGroupbyGroups(dict):
-    def __repr__(self):
-        nitems = get_option('display.max_rows') or len(self)
-
-        fmt = u("{{{things}}}")
-        pfmt = u("{key}: {val}")
-
-        pairs = []
-        for k, v in list(self.items()):
-            pairs.append(pfmt.format(key=k, val=v))
+    """Dict extension to support abbreviated __repr__"""
+    from pandas.io.formats.printing import pprint_thing
 
-        if nitems < len(self):
-            print("Truncating repr")
-            start_cnt, end_cnt = nitems - int(nitems / 2), int(nitems / 2)
-            return fmt.format(things=", ".join(pairs[:start_cnt]) +
-                                     ", ... , " +
-                                     ", ".join(pairs[-end_cnt:]))
-        else:
-            return fmt.format(things=", ".join(pairs))
+    def __repr__(self):
+        return pprint_thing(self, max_seq_items=get_option('display.max_rows'))
 
 
 def ensure_index_from_sequences(sequences, names=None):