BUG/CLN: clarified timedelta inferences

doc/source/release.rst

@@ -62,6 +62,8 @@ API Changes
     when detecting chained assignment, related (:issue:`5938`)
   - DataFrame.head(0) returns self instead of empty frame (:issue:`5846`)
   - ``autocorrelation_plot`` now accepts ``**kwargs``. (:issue:`5623`)
+  - ``convert_objects`` now accepts a ``convert_timedeltas='coerce'`` argument to allow forced dtype conversion of
+    timedeltas (:issue:`5458`,:issue:`5689`)
 
 Experimental Features
 ~~~~~~~~~~~~~~~~~~~~~
@@ -78,12 +80,13 @@ Improvements to existing features
   - support ``dtypes`` property on ``Series/Panel/Panel4D``
   - extend ``Panel.apply`` to allow arbitrary functions (rather than only ufuncs) (:issue:`1148`)
     allow multiple axes to be used to operate on slabs of a ``Panel``
-  - The ``ArrayFormatter``s for ``datetime`` and ``timedelta64`` now intelligently
+  - The ``ArrayFormatter`` for ``datetime`` and ``timedelta64`` now intelligently
     limit precision based on the values in the array (:issue:`3401`)
   - pd.show_versions() is now available for convenience when reporting issues.
   - perf improvements to Series.str.extract (:issue:`5944`)
   - perf improvments in ``dtypes/ftypes`` methods (:issue:`5968`)
   - perf improvments in indexing with object dtypes (:issue:`5968`)
+  - improved dtype inference for ``timedelta`` like passed to constructors (:issue:`5458`,:issue:`5689`)
 
 .. _release.bug_fixes-0.13.1:
 
@@ -122,6 +125,7 @@ Bug Fixes
   - Recent changes in IPython cause warnings to be emitted when using previous versions
     of pandas in QTConsole, now fixed. If you're using an older version and
     need to supress the warnings, see (:issue:`5922`).
+  - Bug in merging ``timedelta`` dtypes (:issue:`5695`)
 
 pandas 0.13.0
 -------------

doc/source/v0.13.1.txt

@@ -3,7 +3,7 @@
 v0.13.1 (???)
 -------------
 
-This is a major release from 0.13.0 and includes a number of API changes, several new features and
+This is a minor release from 0.13.0 and includes a number of API changes, several new features and
 enhancements along with a large number of bug fixes.
 
 Highlights include:
@@ -29,6 +29,27 @@ Deprecations
 Enhancements
 ~~~~~~~~~~~~
 
+- The ``ArrayFormatter`` for ``datetime`` and ``timedelta64`` now intelligently
+  limit precision based on the values in the array (:issue:`3401`)
+
+  Previously output might look like:
+
+  .. code-block:: python
+
+        age                 today               diff
+      0 2001-01-01 00:00:00 2013-04-19 00:00:00 4491 days, 00:00:00
+      1 2004-06-01 00:00:00 2013-04-19 00:00:00 3244 days, 00:00:00
+
+  Now the output looks like:
+
+   .. ipython:: python
+
+      df = DataFrame([ Timestamp('20010101'),
+                       Timestamp('20040601') ], columns=['age'])
+      df['today'] = Timestamp('20130419')
+      df['diff'] = df['today']-df['age']
+      df
+
 - ``Panel.apply`` will work on non-ufuncs. See :ref:`the docs<basics.apply_panel>`.
 
   .. ipython:: python
@@ -83,27 +104,6 @@ Enhancements
      result
      result.loc[:,:,'ItemA']
 
-- The ``ArrayFormatter``s for ``datetime`` and ``timedelta64`` now intelligently
-  limit precision based on the values in the array (:issue:`3401`)
-
-  Previously output might look like:
-
-  .. code-block:: python
-
-        age                 today               diff
-      0 2001-01-01 00:00:00 2013-04-19 00:00:00 4491 days, 00:00:00
-      1 2004-06-01 00:00:00 2013-04-19 00:00:00 3244 days, 00:00:00
-
-  Now the output looks like:
-
-   .. ipython:: python
-
-      df = DataFrame([ Timestamp('20010101'),
-                       Timestamp('20040601') ], columns=['age'])
-      df['today'] = Timestamp('20130419')
-      df['diff'] = df['today']-df['age']
-      df
-
 Experimental
 ~~~~~~~~~~~~
 

pandas/core/common.py

@@ -1514,7 +1514,8 @@ def _values_from_object(o):
 
 
 def _possibly_convert_objects(values, convert_dates=True,
-                              convert_numeric=True):
+                              convert_numeric=True,
+                              convert_timedeltas=True):
     """ if we have an object dtype, try to coerce dates and/or numbers """
 
     # if we have passed in a list or scalar
@@ -1539,6 +1540,22 @@ def _possibly_convert_objects(values, convert_dates=True,
             values = lib.maybe_convert_objects(
                 values, convert_datetime=convert_dates)
 
+    # convert timedeltas
+    if convert_timedeltas and values.dtype == np.object_:
+
+        if convert_timedeltas == 'coerce':
+            from pandas.tseries.timedeltas import \
+                 _possibly_cast_to_timedelta
+            values = _possibly_cast_to_timedelta(values, coerce=True)
+
+            # if we are all nans then leave me alone
+            if not isnull(new_values).all():
+                values = new_values
+
+        else:
+            values = lib.maybe_convert_objects(
+                values, convert_timedelta=convert_timedeltas)
+
     # convert to numeric
     if values.dtype == np.object_:
         if convert_numeric:
@@ -1624,7 +1641,7 @@ def _possibly_cast_to_datetime(value, dtype, coerce=False):
                         elif is_timedelta64:
                             from pandas.tseries.timedeltas import \
                                 _possibly_cast_to_timedelta
-                            value = _possibly_cast_to_timedelta(value)
+                            value = _possibly_cast_to_timedelta(value, coerce='compat')
                     except:
                         pass
 
@@ -1655,7 +1672,7 @@ def _possibly_cast_to_datetime(value, dtype, coerce=False):
                 elif inferred_type in ['timedelta', 'timedelta64']:
                     from pandas.tseries.timedeltas import \
                         _possibly_cast_to_timedelta
-                    value = _possibly_cast_to_timedelta(value)
+                    value = _possibly_cast_to_timedelta(value, coerce='compat')
 
     return value
 

pandas/core/frame.py

@@ -3626,7 +3626,7 @@ def append(self, other, ignore_index=False, verify_integrity=False):
             index = None if other.name is None else [other.name]
             other = other.reindex(self.columns, copy=False)
             other = DataFrame(other.values.reshape((1, len(other))),
-                              index=index, columns=self.columns)
+                              index=index, columns=self.columns).convert_objects()
         elif isinstance(other, list) and not isinstance(other[0], DataFrame):
             other = DataFrame(other)
             if (self.columns.get_indexer(other.columns) >= 0).all():

pandas/core/generic.py

@@ -1844,16 +1844,18 @@ def copy(self, deep=True):
         return self._constructor(data).__finalize__(self)
 
     def convert_objects(self, convert_dates=True, convert_numeric=False,
-                        copy=True):
+                        convert_timedeltas=True, copy=True):
         """
         Attempt to infer better dtype for object columns
 
         Parameters
         ----------
-        convert_dates : if True, attempt to soft convert_dates, if 'coerce',
+        convert_dates : if True, attempt to soft convert dates, if 'coerce',
             force conversion (and non-convertibles get NaT)
         convert_numeric : if True attempt to coerce to numbers (including
             strings), non-convertibles get NaN
+        convert_timedeltas : if True, attempt to soft convert timedeltas, if 'coerce',
+            force conversion (and non-convertibles get NaT)
         copy : Boolean, if True, return copy, default is True
 
         Returns
@@ -1863,6 +1865,7 @@ def convert_objects(self, convert_dates=True, convert_numeric=False,
         return self._constructor(
             self._data.convert(convert_dates=convert_dates,
                                convert_numeric=convert_numeric,
+                               convert_timedeltas=convert_timedeltas,
                                copy=copy)).__finalize__(self)
 
     #----------------------------------------------------------------------
@@ -3174,23 +3177,22 @@ def abs(self):
         -------
         abs: type of caller
         """
-        obj = np.abs(self)
 
         # suprimo numpy 1.6 hacking
+        # for timedeltas
         if _np_version_under1p7:
+
+            def _convert_timedeltas(x):
+                if x.dtype.kind == 'm':
+                    return np.abs(x.view('i8')).astype(x.dtype)
+                return np.abs(x)
+
             if self.ndim == 1:
-                if obj.dtype == 'm8[us]':
-                    obj = obj.astype('m8[ns]')
+                return _convert_timedeltas(self)
             elif self.ndim == 2:
-                def f(x):
-                    if x.dtype == 'm8[us]':
-                        x = x.astype('m8[ns]')
-                    return x
-
-                if 'm8[us]' in obj.dtypes.values:
-                    obj = obj.apply(f)
+                return  self.apply(_convert_timedeltas)
 
-        return obj
+        return np.abs(self)
 
     def pct_change(self, periods=1, fill_method='pad', limit=None, freq=None,
                    **kwds):

pandas/core/internals.py

@@ -1315,8 +1315,8 @@ def is_bool(self):
         """
         return lib.is_bool_array(self.values.ravel())
 
-    def convert(self, convert_dates=True, convert_numeric=True, copy=True,
-                by_item=True):
+    def convert(self, convert_dates=True, convert_numeric=True, convert_timedeltas=True,
+                copy=True, by_item=True):
         """ attempt to coerce any object types to better types
             return a copy of the block (if copy = True)
             by definition we ARE an ObjectBlock!!!!!
@@ -1334,7 +1334,8 @@ def convert(self, convert_dates=True, convert_numeric=True, copy=True,
 
                 values = com._possibly_convert_objects(
                     values.ravel(), convert_dates=convert_dates,
-                    convert_numeric=convert_numeric
+                    convert_numeric=convert_numeric,
+                    convert_timedeltas=convert_timedeltas,
                 ).reshape(values.shape)
                 values = _block_shape(values, ndim=self.ndim)
                 items = self.items.take([i])

pandas/lib.pyx

@@ -14,7 +14,7 @@ from cpython cimport (PyDict_New, PyDict_GetItem, PyDict_SetItem,
                       Py_INCREF, PyTuple_SET_ITEM,
                       PyList_Check, PyFloat_Check,
                       PyString_Check,
-		      PyBytes_Check,
+                      PyBytes_Check,
                       PyTuple_SetItem,
                       PyTuple_New,
                       PyObject_SetAttrString)
@@ -31,7 +31,7 @@ from datetime import datetime as pydatetime
 # this is our tseries.pxd
 from datetime cimport *
 
-from tslib cimport convert_to_tsobject
+from tslib cimport convert_to_tsobject, convert_to_timedelta64
 import tslib
 from tslib import NaT, Timestamp, repr_timedelta64
 

pandas/src/datetime.pxd

@@ -37,6 +37,7 @@ cdef extern from "datetime.h":
     bint PyDateTime_Check(object o)
     bint PyDate_Check(object o)
     bint PyTime_Check(object o)
+    bint PyDelta_Check(object o)
     object PyDateTime_FromDateAndTime(int year, int month, int day, int hour,
                                       int minute, int second, int us)