Fixes for review comments from pandas-dev#15067.

Still need to improve unit testing.

Author: jgoppert

doc/source/visualization.rst

@@ -1245,6 +1245,16 @@ in ``pandas.plot_params`` can be used in a `with statement`:
 
    plt.close('all')
 
+Automatic Date Tick Adjustment
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Especially for the ``TimedeltaIndex`` that uses native matplotlib
+tick locator methods, it is useful to call the automatic
+date tick adjustment from matplotlib for figures whose ticklabels overlap.
+
+See the :meth:`autofmt_xdate <matplotlib.figure.autofmt_xdate>` method and the
+`matplotlib documentation <http://matplotlib.org/api/figure_api.html#matplotlib.figure.Figure.autofmt_xdate>`__ for more.
+
 Subplots
 ~~~~~~~~
 

doc/source/whatsnew/v0.20.0.txt

@@ -116,6 +116,7 @@ Other enhancements
 
 - ``.select_dtypes()`` now allows the string 'datetimetz' to generically select datetimes with tz (:issue:`14910`)
 
+- ``pd.TimedeltaIndex`` now has a custom datetick formatter specifically designed for nanosecond level precision (:issue:`8711`)
 
 .. _whatsnew_0200.api_breaking:
 

pandas/tests/plotting/test_datetimelike.py

@@ -7,6 +7,7 @@
 from pandas import Index, Series, DataFrame
 
 from pandas.tseries.index import date_range, bdate_range
+from pandas.tseries.tdi import timedelta_range
 from pandas.tseries.offsets import DateOffset
 from pandas.tseries.period import period_range, Period, PeriodIndex
 from pandas.tseries.resample import DatetimeIndex
@@ -1271,6 +1272,22 @@ def test_plot_outofbounds_datetime(self):
         values = [datetime(1677, 1, 1, 12), datetime(1677, 1, 2, 12)]
         self.plt.plot(values)
 
+    def test_format_timedelta_ticks(self):
+        import matplotlib.pyplot as plt
+        rng = timedelta_range('0', periods=3, freq='ns')
+        df = DataFrame(np.random.randn(len(rng), 3), rng)
+        ax = df.plot()
+        plt.gcf().autofmt_xdate()
+        xaxis = ax.get_xaxis()
+        for l in xaxis.get_ticklabels():
+            if len(l.get_text()) > 0:
+                self.assertEqual(l.get_rotation(), 30)
+
+    def test_timedelta_plot(self):
+        # test issue #8711
+        s = Series(range(5), timedelta_range('1day', periods=5))
+        _check_plot_works(s.plot)
+
 
 def _check_plot_works(f, freq=None, series=None, *args, **kwargs):
     import matplotlib.pyplot as plt

pandas/tseries/plotting.py

@@ -280,7 +280,7 @@ def _maybe_convert_index(ax, data):
 # Patch methods for subplot. Only format_dateaxis is currently used.
 # Do we need the rest for convenience?
 
-def timeTicks(x, pos, n_decimals):
+def format_timedelta_ticks(x, pos, n_decimals):
     ''' Convert seconds to 'D days HH:MM:SS.F' '''
     s, ns = divmod(x, 1e9)
     m, s = divmod(s, 60)
@@ -306,6 +306,8 @@ def format_dateaxis(subplot, freq, index):
     """
 
     # handle index specific formatting
+    # Note: DatetimeIndex does not use this
+    # interface. DatetimeIndex uses matplotlib.date directly
     if isinstance(index, PeriodIndex):
 
         majlocator = TimeSeries_DateLocator(freq, dynamic_mode=True,
@@ -326,23 +328,20 @@ def format_dateaxis(subplot, freq, index):
         subplot.xaxis.set_major_formatter(majformatter)
         subplot.xaxis.set_minor_formatter(minformatter)
 
+        # x and y coord info
+        subplot.format_coord = lambda t, y: (
+            "t = {0}  y = {1:8f}".format(Period(ordinal=int(t), freq=freq), y))
+
     elif isinstance(index, TimedeltaIndex):
         from matplotlib import ticker
         (vmin, vmax) = tuple(subplot.xaxis.get_view_interval())
         n_decimals = int(np.ceil(np.log10(100 * 1e9 / (vmax - vmin))))
         if n_decimals > 9:
             n_decimals = 9
         formatter = ticker.FuncFormatter(
-            lambda x, pos: timeTicks(x, pos, n_decimals))
+            lambda x, pos: format_timedelta_ticks(x, pos, n_decimals))
         subplot.xaxis.set_major_formatter(formatter)
     else:
         raise IOError('index type not supported')
 
-    # Note, DatetimeIndex does not use this
-    # interface. DatetimeIndex uses matplotlib.date directly
-
-    # x and y coord info
-    subplot.format_coord = lambda t, y: (
-        "t = {0}  y = {1:8f}".format(Period(ordinal=int(t), freq=freq), y))
-
     pylab.draw_if_interactive()