matplotlib
diff --git a/‎lib/matplotlib/colorbar.py‎
Lines changed: 9 additions & 5 deletions b/‎lib/matplotlib/colorbar.py‎
Lines changed: 9 additions & 5 deletions
diff --git a/‎lib/matplotlib/tests/baseline_images/test_colorbar/nonorm_colorbars.svg‎
Lines changed: 151 additions & 0 deletions b/‎lib/matplotlib/tests/baseline_images/test_colorbar/nonorm_colorbars.svg‎
Lines changed: 151 additions & 0 deletions
diff --git a/‎lib/matplotlib/tests/test_colorbar.py‎
Lines changed: 18 additions & 2 deletions b/‎lib/matplotlib/tests/test_colorbar.py‎
Lines changed: 18 additions & 2 deletions
@@ -824,6 +824,12 @@ def _get_ticker_locator_formatter(self):
             b = self.norm.boundaries
             if locator is None:
                 locator = ticker.FixedLocator(b, nbins=10)
+        elif isinstance(self.norm, colors.NoNorm):
+            if locator is None:
+                # put ticks on integers between the boundaries of NoNorm
+                nv = len(self._values)
+                base = 1 + int(nv / 10)
+                locator = ticker.IndexLocator(base=base, offset=.5)
         elif self.boundaries is not None:
             b = self._boundaries[self._inside]
             if locator is None:
@@ -835,11 +841,6 @@ def _get_ticker_locator_formatter(self):
                 locator = self._long_axis().get_major_locator()
             if minorlocator is None:
                 minorlocator = self._long_axis().get_minor_locator()
-            if isinstance(self.norm, colors.NoNorm):
-                # default locator:
-                nv = len(self._values)
-                base = 1 + int(nv / 10)
-                locator = ticker.IndexLocator(base=base, offset=0)
 
         if minorlocator is None:
             minorlocator = ticker.NullLocator()
@@ -1097,6 +1098,9 @@ def _process_values(self):
         # otherwise values are set from the boundaries
         if isinstance(self.norm, colors.BoundaryNorm):
             b = self.norm.boundaries
+        elif isinstance(self.norm, colors.NoNorm):
+            # NoNorm has N blocks, so N+1 boundaries, centered on integers:
+            b = np.arange(self.cmap.N + 1) - .5
         else:
             # otherwise make the boundaries from the size of the cmap:
             N = self.cmap.N + 1
 
@@ -7,10 +7,11 @@
 from matplotlib import rc_context
 from matplotlib.testing.decorators import image_comparison
 import matplotlib.pyplot as plt
-from matplotlib.colors import BoundaryNorm, LogNorm, PowerNorm, Normalize
+from matplotlib.colors import (
+    BoundaryNorm, LogNorm, PowerNorm, Normalize, NoNorm
+)
 from matplotlib.colorbar import Colorbar
 from matplotlib.ticker import FixedLocator
-
 from matplotlib.testing.decorators import check_figures_equal
 
 
@@ -913,3 +914,18 @@ def test_negative_boundarynorm():
     cb = fig.colorbar(cm.ScalarMappable(cmap=cmap, norm=norm), cax=ax)
     np.testing.assert_allclose(cb.ax.get_ylim(), [clevs[0], clevs[-1]])
     np.testing.assert_allclose(cb.ax.get_yticks(), clevs)
+
+
+@image_comparison(['nonorm_colorbars.svg'], remove_text=False,
+                  style='mpl20')
+def test_nonorm():
+    plt.rcParams['svg.fonttype'] = 'none'
+    data = [1, 2, 3, 4, 5]
+
+    fig, ax = plt.subplots(figsize=(6, 1))
+    fig.subplots_adjust(bottom=0.5)
+
+    norm = NoNorm(vmin=min(data), vmax=max(data))
+    cmap = cm.get_cmap("viridis", len(data))
+    mappable = cm.ScalarMappable(norm=norm, cmap=cmap)
+    cbar = fig.colorbar(mappable, cax=ax, orientation="horizontal")