ENH/BUG: partial string indexing with PeriodIndex

doc/source/release.rst

@@ -498,6 +498,7 @@ Bug Fixes
 - Bug in ``Dataframe.set_index``, ``reindex`` and ``pivot`` don't preserve ``DatetimeIndex`` and ``PeriodIndex`` attributes (:issue:`3950`, :issue:`5878`, :issue:`6631`)
 - Bug in ``MultiIndex.get_level_values`` doesn't preserve ``DatetimeIndex`` and ``PeriodIndex`` attributes (:issue:`7092`)
 - Bug in ``Groupby`` doesn't preserve ``tz`` (:issue:`3950`)
+- Bug in ``PeriodIndex`` partial string slicing (:issue:`6716`)
 
 pandas 0.13.1
 -------------

doc/source/timeseries.rst

@@ -299,8 +299,10 @@ intelligent functionality like selection, slicing, etc.
    ts[:5].index
    ts[::2].index
 
-Partial String Indexing
-~~~~~~~~~~~~~~~~~~~~~~~
+.. _timeseries.partialindexing:
+
+DatetimeIndex Partial String Indexing
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 You can pass in dates and strings that parse to dates as indexing parameters:
 
@@ -1092,7 +1094,38 @@ objects:
 
 .. ipython:: python
 
-   Series(randn(len(prng)), prng)
+   ps = Series(randn(len(prng)), prng)
+   ps
+
+PeriodIndex Partial String Indexing
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+You can pass in dates and strings to `Series` and `DataFrame` with `PeriodIndex`, as the same manner as `DatetimeIndex`. For details, refer to :ref:`DatetimeIndex Partial String Indexing <timeseries.partialindexing>`.
+
+.. ipython:: python
+
+   ps['2011-01']
+
+   ps[datetime(2011, 12, 25):]
+
+   ps['10/31/2011':'12/31/2011']
+
+Passing string represents lower frequency than `PeriodIndex` returns partial sliced data.
+
+.. ipython:: python
+
+   ps['2011']
+
+   dfp = DataFrame(randn(600,1), columns=['A'],
+                   index=period_range('2013-01-01 9:00', periods=600, freq='T'))
+   dfp
+   dfp['2013-01-01 10H']
+
+As the same as `DatetimeIndex`, the endpoints will be included in the result. Below example slices data starting from 10:00 to 11:59. 
+
+.. ipython:: python
+
+   dfp['2013-01-01 10H':'2013-01-01 11H']
 
 Frequency Conversion and Resampling with PeriodIndex
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

doc/source/v0.14.0.txt

@@ -591,6 +591,15 @@ Enhancements
 
 - str.wrap implemented (:issue:`6999`)
 
+- `PeriodIndex` fully supports partial string indexing like `DatetimeIndex` (:issue:`7043`)
+
+  .. ipython:: python
+
+     prng = period_range('2013-01-01 09:00', periods=100, freq='H')
+     ps = Series(np.random.randn(len(prng)), index=prng)
+     ps
+     ps['2013-01-02']
+
 .. _whatsnew_0140.performance:
 
 Performance

pandas/tseries/period.py

@@ -908,13 +908,13 @@ def get_value(self, series, key):
                     pos = np.searchsorted(self.values, [ord1, ord2])
                     key = slice(pos[0], pos[1] + 1)
                     return series[key]
-                else:
+                elif grp == freqn:
                     key = Period(asdt, freq=self.freq).ordinal
                     return _maybe_box(self, self._engine.get_value(s, key), series, key)
+                else:
+                    raise KeyError(key)
             except TypeError:
                 pass
-            except KeyError:
-                pass
 
             key = Period(key, self.freq).ordinal
             return _maybe_box(self, self._engine.get_value(s, key), series, key)
@@ -978,8 +978,10 @@ def _get_string_slice(self, key):
             raise ValueError('Partial indexing only valid for '
                              'ordered time series')
 
-        asdt, parsed, reso = parse_time_string(key, self.freq)
-        key = asdt
+        key, parsed, reso = parse_time_string(key, self.freq)
+
+        grp = _freq_mod._infer_period_group(reso)
+        freqn = _freq_mod._period_group(self.freq)
 
         if reso == 'year':
             t1 = Period(year=parsed.year, freq='A')
@@ -988,6 +990,19 @@ def _get_string_slice(self, key):
         elif reso == 'quarter':
             q = (parsed.month - 1) // 3 + 1
             t1 = Period(year=parsed.year, quarter=q, freq='Q-DEC')
+        elif reso == 'day' and grp < freqn:
+            t1 = Period(year=parsed.year, month=parsed.month, day=parsed.day,
+                        freq='D')
+        elif reso == 'hour' and grp < freqn:
+            t1 = Period(year=parsed.year, month=parsed.month, day=parsed.day,
+                        hour=parsed.hour, freq='H')
+        elif reso == 'minute' and grp < freqn:
+            t1 = Period(year=parsed.year, month=parsed.month, day=parsed.day,
+                        hour=parsed.hour, minute=parsed.minute, freq='T')
+        elif reso == 'second' and grp < freqn:
+            t1 = Period(year=parsed.year, month=parsed.month, day=parsed.day,
+                        hour=parsed.hour, minute=parsed.minute, second=parsed.second,
+                        freq='S')
         else:
             raise KeyError(key)
 

pandas/tseries/tests/test_period.py

@@ -1851,6 +1851,97 @@ def test_pindex_slice_index(self):
         exp = s[12:24]
         assert_series_equal(res, exp)
 
+    def test_getitem_day(self):
+        # GH 6716
+        # Confirm DatetimeIndex and PeriodIndex works identically
+        didx = DatetimeIndex(start='2013/01/01', freq='D', periods=400)
+        pidx = PeriodIndex(start='2013/01/01', freq='D', periods=400)
+
+        for idx in [didx, pidx]:
+            # getitem against index should raise ValueError
+            values = ['2014', '2013/02', '2013/01/02',
+                      '2013/02/01 9H', '2013/02/01 09:00']
+            for v in values:
+                with tm.assertRaises(ValueError):
+                    idx[v]
+
+            s = Series(np.random.rand(len(idx)), index=idx)
+            assert_series_equal(s['2013/01'], s[0:31])
+            assert_series_equal(s['2013/02'], s[31:59])
+            assert_series_equal(s['2014'], s[365:])
+
+            invalid = ['2013/02/01 9H', '2013/02/01 09:00']
+            for v in invalid:
+                with tm.assertRaises(KeyError):
+                    s[v]
+
+    def test_range_slice_day(self):
+        # GH 6716
+        didx = DatetimeIndex(start='2013/01/01', freq='D', periods=400)
+        pidx = PeriodIndex(start='2013/01/01', freq='D', periods=400)
+
+        for idx in [didx, pidx]:
+            # slices against index should raise IndexError
+            values = ['2014', '2013/02', '2013/01/02',
+                      '2013/02/01 9H', '2013/02/01 09:00']
+            for v in values:
+                with tm.assertRaises(IndexError):
+                    idx[v:]
+
+            s = Series(np.random.rand(len(idx)), index=idx)
+
+            assert_series_equal(s['2013/01/02':], s[1:])
+            assert_series_equal(s['2013/01/02':'2013/01/05'], s[1:5])
+            assert_series_equal(s['2013/02':], s[31:])
+            assert_series_equal(s['2014':], s[365:])
+
+            invalid = ['2013/02/01 9H', '2013/02/01 09:00']
+            for v in invalid:
+                with tm.assertRaises(IndexError):
+                    idx[v:]
+
+    def test_getitem_seconds(self):
+        # GH 6716
+        didx = DatetimeIndex(start='2013/01/01 09:00:00', freq='S', periods=4000)
+        pidx = PeriodIndex(start='2013/01/01 09:00:00', freq='S', periods=4000)
+
+        for idx in [didx, pidx]:
+            # getitem against index should raise ValueError
+            values = ['2014', '2013/02', '2013/01/02',
+                      '2013/02/01 9H', '2013/02/01 09:00']
+            for v in values:
+                with tm.assertRaises(ValueError):
+                    idx[v]
+
+            s = Series(np.random.rand(len(idx)), index=idx)
+
+            assert_series_equal(s['2013/01/01 10:00'], s[3600:3660])
+            assert_series_equal(s['2013/01/01 9H'], s[:3600])
+            for d in ['2013/01/01', '2013/01', '2013']:
+                assert_series_equal(s[d], s)
+
+    def test_range_slice_seconds(self):
+        # GH 6716
+        didx = DatetimeIndex(start='2013/01/01 09:00:00', freq='S', periods=4000)
+        pidx = PeriodIndex(start='2013/01/01 09:00:00', freq='S', periods=4000)
+
+        for idx in [didx, pidx]:
+            # slices against index should raise IndexError
+            values = ['2014', '2013/02', '2013/01/02',
+                      '2013/02/01 9H', '2013/02/01 09:00']
+            for v in values:
+                with tm.assertRaises(IndexError):
+                    idx[v:]
+
+            s = Series(np.random.rand(len(idx)), index=idx)
+
+            assert_series_equal(s['2013/01/01 09:05':'2013/01/01 09:10'], s[300:660])
+            assert_series_equal(s['2013/01/01 10:00':'2013/01/01 10:05'], s[3600:3960])
+            assert_series_equal(s['2013/01/01 10H':], s[3600:])
+            assert_series_equal(s[:'2013/01/01 09:30'], s[:1860])
+            for d in ['2013/01/01', '2013/01', '2013']:
+                assert_series_equal(s[d:], s)
+
     def test_pindex_qaccess(self):
         pi = PeriodIndex(['2Q05', '3Q05', '4Q05', '1Q06', '2Q06'], freq='Q')
         s = Series(np.random.rand(len(pi)), index=pi).cumsum()