BUG: don't copy int64 arrays in DatetimeIndex ctor when copy=False, c…

…lose #1624

RELEASE.rst

@@ -29,6 +29,7 @@ pandas 0.8.1
 
 **New features**
 
+  - Add vectorized, NA-friendly string methods to Series (#1621, #620)
   - Can pass dict of per-column line styles to DataFrame.plot (#1559)
   - Add new ``bootstrap_plot`` plot function
   - Add new ``parallel_coordinates`` plot function (#1488)
@@ -82,6 +83,7 @@ pandas 0.8.1
   - Fix unit test errors on Python 3 (#1550)
   - Fix .ix indexing bugs in duplicate DataFrame index (#1201)
   - Better handle errors with non-existing objects in HDFStore (#1254)
+  - Don't copy int64 array data in DatetimeIndex when copy=False (#1624)
 
 pandas 0.8.0
 ============

pandas/tseries/index.py

@@ -208,7 +208,10 @@ def __new__(cls, data=None,
                 else:
                     subarr = data
         elif data.dtype == _INT64_DTYPE:
-            subarr = np.asarray(data, dtype=_NS_DTYPE)
+            if copy:
+                subarr = np.asarray(data, dtype=_NS_DTYPE)
+            else:
+                subarr = data.view(_NS_DTYPE)
         else:
             subarr = tools.to_datetime(data)
             if not np.issubdtype(subarr.dtype, np.datetime64):

pandas/tseries/tests/test_timeseries.py

@@ -1012,6 +1012,19 @@ def test_datetimeindex_repr_short(self):
         dr = date_range(start='1/1/2012', periods=3)
         repr(dr)
 
+    def test_constructor_int64_nocopy(self):
+        # #1624
+        arr = np.arange(1000)
+        index = DatetimeIndex(arr)
+
+        arr[50:100] = -1
+        self.assert_((index.asi8[50:100] == -1).all())
+
+        arr = np.arange(1000)
+        index = DatetimeIndex(arr, copy=True)
+
+        arr[50:100] = -1
+        self.assert_((index.asi8[50:100] != -1).all())
 
 def _simple_ts(start, end, freq='D'):
     rng = date_range(start, end, freq=freq)