final changes

Author: max-sixty

doc/source/whatsnew/v0.20.0.txt

@@ -291,6 +291,7 @@ Bug Fixes
 - Bug in ``describe()`` when passing a numpy array which does not contain the median to the ``percentiles`` keyword argument (:issue:`14908`)
 - Bug in ``DataFrame.sort_values()`` when sorting by multiple columns where one column is of type ``int64`` and contains ``NaT`` (:issue:`14922`)
 - Bug in ``DataFrame.reindex()`` in which ``method`` was ignored when passing ``columns`` (:issue:`14992`)
+- Cleaned up ``PeriodIndex`` constructor, including raising on floats more consistently (:issue:`13277`)
 
 
 - Bug in ``pd.read_msgpack()`` in which ``Series`` categoricals were being improperly processed (:issue:`14901`)

pandas/indexes/base.py

@@ -86,7 +86,8 @@ def _new_Index(cls, d):
     """ This is called upon unpickling, rather than the default which doesn't
     have arguments and breaks __new__
     """
-    from pandas.types.generic import ABCPeriodIndex
+    # required for backward compat, because PI can't be instantiated with
+    # ordinals through __new__ GH #13277
     if issubclass(cls, ABCPeriodIndex):
         if d['data'].dtype == 'int64':
             values = d.pop('data')