Merge pull request matplotlib#17269 from leolchat/patch-1

dstansby · web-flow · commit 033904247814 · 2020-07-25T18:51:58.000+01:00
Fix ConciseDateFormatter when plotting a range included in a second
diff --git a/lib/matplotlib/dates.py b/lib/matplotlib/dates.py
@@ -796,6 +796,10 @@ def format_ticks(self, values):
         for level in range(5, -1, -1):
             if len(np.unique(tickdate[:, level])) > 1:
                 break
+            elif level == 0:
+                # all tickdate are the same, so only micros might be different
+                # set to the most precise (6: microseconds doesn't exist...)
+                level = 5
 
         # level is the basic level we will label at.
         # now loop through and decide the actual ticklabels
diff --git a/lib/matplotlib/tests/test_dates.py b/lib/matplotlib/tests/test_dates.py
@@ -449,6 +449,17 @@ def _create_auto_date_locator(date1, date2):
         assert list(map(str, mdates.num2date(locator()))) == expected
 
 
+def test_concise_formatter_subsecond():
+    locator = mdates.AutoDateLocator(interval_multiples=True)
+    formatter = mdates.ConciseDateFormatter(locator)
+    year_1996 = 9861.0
+    strings = formatter.format_ticks([
+        year_1996,
+        year_1996 + 500 / mdates.MUSECONDS_PER_DAY,
+        year_1996 + 900 / mdates.MUSECONDS_PER_DAY])
+    assert strings == ['00:00', '00.0005', '00.0009']
+
+
 def test_concise_formatter():
     def _create_auto_date_locator(date1, date2):
         fig, ax = plt.subplots()
