avoid the case that divides by zero (+ test)

afvincent · afvincent · commit f51fa53ecfe1 · 2017-10-17T18:09:56.000-07:00
diff --git a/lib/matplotlib/tests/test_ticker.py b/lib/matplotlib/tests/test_ticker.py
@@ -80,6 +80,15 @@ def test_basic(self):
                                0.95, 1, 1.05, 1.1, 1.15, 1.25, 1.3, 1.35])
         assert_almost_equal(ax.xaxis.get_ticklocs(minor=True), test_value)
 
+    def test_single_majorloc(self):
+        # related to issue 8804
+        fig, ax = plt.subplots()
+        ax.set_xlim(-0.9, 0.9)
+        ax.set_xticks([0])  # force a single major tick position
+        ax.minorticks_on()
+        ax.xaxis.set_minor_locator(mticker.AutoMinorLocator())
+        assert len(ax.xaxis.get_minorticklocs()) == 0
+
 
 class TestLogLocator(object):
     def test_basic(self):
diff --git a/lib/matplotlib/ticker.py b/lib/matplotlib/ticker.py
@@ -2545,7 +2545,7 @@ def __call__(self):
         if vmin > vmax:
             vmin, vmax = vmax, vmin
 
-        if len(majorlocs) > 0:
+        if len(majorlocs) >= 2:
             t0 = majorlocs[0]
             tmin = ((vmin - t0) // minorstep + 1) * minorstep
             tmax = ((vmax - t0) // minorstep + 1) * minorstep
