Merge pull request matplotlib#1636 from mdboom/hexbin-log

hexbin log scale is broken in matplotlib 1.2.0

Author: dmcdougall

lib/matplotlib/axes.py

@@ -5443,7 +5443,7 @@ def errorbar(self, x, y, yerr=None, xerr=None,
             lines_kw['transform'] = kwargs['transform']
         if 'zorder' in kwargs:
             lines_kw['zorder'] = kwargs['zorder']
-            
+
         # arrays fine here, they are booleans and hence not units
         if not iterable(lolims):
             lolims = np.asarray([lolims]*len(x), bool)
@@ -6432,32 +6432,39 @@ def hexbin(self, x, y, C = None, gridsize = 100, bins = None,
         offsets = offsets[good_idxs,:]
         accum = accum[good_idxs]
 
-        if xscale=='log':
-            offsets[:,0] = 10**(offsets[:,0])
-            xmin = 10**xmin
-            xmax = 10**xmax
-            self.set_xscale('log')
-        if yscale=='log':
-            offsets[:,1] = 10**(offsets[:,1])
-            ymin = 10**ymin
-            ymax = 10**ymax
-            self.set_yscale('log')
-
         polygon = np.zeros((6, 2), float)
         polygon[:,0] = sx * np.array([ 0.5, 0.5, 0.0, -0.5, -0.5,  0.0])
         polygon[:,1] = sy * np.array([-0.5, 0.5, 1.0,  0.5, -0.5, -1.0]) / 3.0
 
         if edgecolors=='none':
             edgecolors = 'face'
 
-        collection = mcoll.PolyCollection(
-            [polygon],
-            edgecolors = edgecolors,
-            linewidths = linewidths,
-            offsets = offsets,
-            transOffset = mtransforms.IdentityTransform(),
-            offset_position = "data"
-            )
+        if xscale == 'log' or yscale == 'log':
+            polygons = np.expand_dims(polygon, 0) + np.expand_dims(offsets, 1)
+            if xscale == 'log':
+                polygons[:, :, 0] = 10.0 ** polygons[:, :, 0]
+                xmin = 10.0 ** xmin
+                xmax = 10.0 ** xmax
+                self.set_xscale(xscale)
+            if yscale == 'log':
+                polygons[:, :, 1] = 10.0 ** polygons[:, :, 1]
+                ymin = 10.0 ** ymin
+                ymax = 10.0 ** ymax
+                self.set_yscale(yscale)
+            collection = mcoll.PolyCollection(
+                polygons,
+                edgecolors=edgecolors,
+                linewidths=linewidths,
+                )
+        else:
+            collection = mcoll.PolyCollection(
+                [polygon],
+                edgecolors=edgecolors,
+                linewidths=linewidths,
+                offsets=offsets,
+                transOffset=mtransforms.IdentityTransform(),
+                offset_position="data"
+                )
 
         if isinstance(norm, mcolors.LogNorm):
             if (accum==0).any():

lib/matplotlib/tests/baseline_images/test_axes/hexbin_log.png

@@ -419,6 +419,21 @@ def test_hexbin_extent():
 
     ax.hexbin(x, y, extent=[.1, .3, .6, .7])
 
+@image_comparison(baseline_images=['hexbin_log'],
+                  remove_text=True,
+                  extensions=['png'])
+def test_hexbin_log():
+    # Issue #1636
+    fig = plt.figure()
+
+    np.random.seed(0)
+    n = 100000
+    x = np.random.standard_normal(n)
+    y = 2.0 + 3.0 * x + 4.0 * np.random.standard_normal(n)
+    y = np.power(2, y * 0.5)
+    ax = fig.add_subplot(111)
+    ax.hexbin(x, y, yscale='log')
+
 @cleanup
 def test_inverted_limits():
     # Test gh:1553