From c0803f0d18fc19203950238aa2f9a0baaa98af15 Mon Sep 17 00:00:00 2001
From: Eric Firing <efiring@hawaii.edu>
Date: Tue, 25 Aug 2015 09:02:00 -1000
Subject: [PATCH] BUG: in ScalarFormatter, handle two identical locations;
 closes #4761

---
 lib/matplotlib/ticker.py | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/lib/matplotlib/ticker.py b/lib/matplotlib/ticker.py
index c3bc178f8865..586373468f0f 100644
--- a/lib/matplotlib/ticker.py
+++ b/lib/matplotlib/ticker.py
@@ -585,6 +585,12 @@ def _set_format(self, vmin, vmax):
             _locs = self.locs
         locs = (np.asarray(_locs) - self.offset) / 10. ** self.orderOfMagnitude
         loc_range = np.ptp(locs)
+        # Curvilinear coordinates can yield two identical points.
+        if loc_range == 0:
+            loc_range = np.max(np.abs(locs))
+        # Both points might be zero.
+        if loc_range == 0:
+            loc_range = 1
         if len(self.locs) < 2:
             # We needed the end points only for the loc_range calculation.
             locs = locs[:-2]