Merge pull request #130 from plotly/andrew-fix-pandas-date-formatter

Andrew fix pandas date formatter

Author: theengineear

plotly/matplotlylib/mpltools.py

@@ -7,8 +7,9 @@
 
 import math
 import warnings
-import datetime
 import matplotlib.dates
+import pytz
+
 
 def check_bar_match(old_bar, new_bar):
     """Check if two bars belong in the same collection (bar chart).
@@ -418,7 +419,7 @@ def prep_ticks(ax, index, ax_type, props):
         return dict()
     # get tick label formatting information
     formatter = axis.get_major_formatter().__class__.__name__
-    if ax_type == 'x' and formatter == 'DateFormatter':
+    if ax_type == 'x' and 'DateFormatter' in formatter:
         axis_dict['type'] = 'date'
         try:
             axis_dict['tick0'] = mpl_dates_to_datestrings(axis_dict['tick0'])
@@ -455,13 +456,15 @@ def prep_xy_axis(ax, props, x_bounds, y_bounds):
     yaxis.update(prep_ticks(ax, 1, 'y', props))
     return xaxis, yaxis
 
+
 def mpl_dates_to_datestrings(mpl_dates, format_string="%Y-%m-%d %H:%M:%S"):
+    """Convert matplotlib dates to formatted datestrings for plotly.
+
+    Info on mpl dates: http://matplotlib.org/api/dates_api.html
+
+    """
     try:
-        # make sure we have a list
-        mpl_date_list = list(mpl_dates)
-        epoch_times = matplotlib.dates.num2epoch(mpl_date_list)
-        date_times = [datetime.datetime.utcfromtimestamp(epoch_time)
-                      for epoch_time in epoch_times]
+        date_times = matplotlib.dates.num2date(mpl_dates, tz=pytz.utc)
         time_strings = [date_time.strftime(format_string)
                         for date_time in date_times]
         if len(time_strings) > 1:

plotly/tests/test_optional/test_matplotlylib/test_date_times.py

@@ -0,0 +1,40 @@
+from __future__ import absolute_import
+import matplotlib
+# Force matplotlib to not use any Xwindows backend.
+matplotlib.use('Agg')
+import matplotlib.pyplot as plt
+import datetime
+from matplotlib.dates import date2num
+import plotly.tools as tls
+from unittest import TestCase
+
+from plotly.tests.test_optional.optional_utils import compare_dict, run_fig
+
+
+class TestDateTimes(TestCase):
+    def test_normal_mpl_dates(self):
+        datetime_format = '%Y-%m-%d %H:%M:%S'
+        y = [1, 2, 3, 4]
+        date_strings = ['2010-01-04 00:00:00',
+                        '2010-01-04 10:00:00',
+                        '2010-01-04 23:00:59',
+                        '2010-01-05 00:00:00']
+
+        # 1. create datetimes from the strings
+        dates = [datetime.datetime.strptime(date_string, datetime_format)
+                 for date_string in date_strings]
+
+        # 2. create the mpl_dates from these datetimes
+        mpl_dates = date2num(dates)
+
+        # make a figure in mpl
+        fig, ax = plt.subplots()
+        ax.plot_date(mpl_dates, y)
+
+        # convert this figure to plotly's graph_objs
+        pfig = tls.mpl_to_plotly(fig)
+
+        print date_strings
+        print pfig['data'][0]['x']
+        # we use the same format here, so we expect equality here
+        self.assertEqual(pfig['data'][0]['x'], date_strings)