ENH: datetime.time converters for plotting

Author: Chang She

pandas/src/datetime.pxd

@@ -34,6 +34,7 @@ cdef extern from "datetime.h":
     int PyDateTime_TIME_GET_MICROSECOND(object o)
     bint PyDateTime_Check(object o)
     bint PyDate_Check(object o)
+    bint PyTime_Check(object o)
     object PyDateTime_FromDateAndTime(int year, int month, int day, int hour,
                                       int minute, int second, int us)
 

pandas/src/inference.pyx

@@ -103,6 +103,9 @@ cdef inline bint is_datetime(object o):
 cdef inline bint is_date(object o):
     return PyDate_Check(o)
 
+cdef inline bint is_time(object o):
+    return PyTime_Check(o)
+
 def is_bool_array(ndarray values):
     cdef:
         Py_ssize_t i, n = len(values)
@@ -240,6 +243,14 @@ def is_date_array(ndarray[object] values):
             return False
     return True
 
+def is_time_array(ndarray[object] values):
+    cdef int i, n = len(values)
+    if n == 0:
+        return False
+    for i in range(n):
+        if not is_time(values[i]):
+            return False
+    return True
 
 def maybe_convert_numeric(ndarray[object] values, set na_values,
                           convert_empty=True):

pandas/tools/plotting.py

@@ -16,6 +16,12 @@
 import pandas.tseries.tools as datetools
 import pandas.lib as lib
 
+try: # mpl optional
+    import pandas.tseries.converter as conv
+    conv.register()
+except ImportError:
+    pass
+
 def _get_standard_kind(kind):
     return {'density' : 'kde'}.get(kind, kind)
 
@@ -492,8 +498,9 @@ def plt(self):
 
     def _get_xticks(self, convert_period=False):
         index = self.data.index
-        is_datetype = index.inferred_type in ('datetime', 'date',
-                                              'datetime64')
+        is_datetype = (index.inferred_type in ('datetime', 'date',
+                                               'datetime64')
+                       or lib.is_time_array(index))
 
         if self.use_index:
             if convert_period and isinstance(index, PeriodIndex):
@@ -508,6 +515,7 @@ def _get_xticks(self, convert_period=False):
                 """
                 x = index._mpl_repr()
             else:
+                foo
                 self._need_to_set_index = True
                 x = range(len(index))
         else:
@@ -578,40 +586,6 @@ def _post_plot_logic(self):
         if self.subplots and self.legend:
             self.axes[0].legend(loc='best')
 
-try: # matplotlib is optional dependency
-    import matplotlib.units as units
-    import matplotlib.dates as dates
-
-    class DatetimeConverter(dates.DateConverter):
-
-        @staticmethod
-        def convert(values, unit, axis):
-            def try_parse(values):
-                try:
-                    return datetools.to_datetime(values).toordinal()
-                except Exception:
-                    return values
-
-            if isinstance(values, (datetime.datetime, datetime.date)):
-                return values.toordinal()
-            elif isinstance(values, (datetime.time)):
-                return dates.date2num(values)
-            elif (com.is_integer(values) or com.is_float(values)):
-                return values
-            elif isinstance(values, str):
-                return try_parse(values)
-            elif isinstance(values, Index):
-                return values.map(try_parse)
-            elif isinstance(values, (list, tuple, np.ndarray)):
-                return [try_parse(x) for x in values]
-            return values
-
-    units.registry[lib.Timestamp] = DatetimeConverter()
-    units.registry[datetime.date] = DatetimeConverter()
-    units.registry[datetime.datetime] = DatetimeConverter()
-except ImportError:
-    pass
-
 class LinePlot(MPLPlot):
 
     def __init__(self, data, **kwargs):