fix numdec computation for symlog axes

matplotlib · tacaswell · Aug 22, 2016 · Oct 1, 2015 · Oct 9, 2015 · Oct 15, 2015
commit ad0a7518701fd41aa4eb7258c6307f3cace9a66a
diff --git a/lib/matplotlib/scale.py b/lib/matplotlib/scale.py
@@ -465,7 +465,7 @@ def set_default_locators_and_formatters(self, axis):
        axis.set_major_formatter(LogFormatterSciNotation(self.base))
        axis.set_minor_locator(SymmetricalLogLocator(self.get_transform(),
                                                     self.subs))
-        axis.set_minor_formatter(LogFormatterSciNotation(self.base))
+        axis.set_minor_formatter(NullFormatter())

    def get_transform(self):
        """

diff --git a/lib/matplotlib/ticker.py b/lib/matplotlib/ticker.py
@@ -845,10 +845,24 @@ def set_locs(self, locs):

        vmin, vmax = self.axis.get_view_interval()
        self.d = abs(vmax - vmin)
-        vmin = math.log(vmin) / math.log(b)
-        vmax = math.log(vmax) / math.log(b)

-        numdec = abs(vmax - vmin)
+        if hasattr(self.axis.get_transform(), 'linthresh'):
+            t = self.axis.get_transform()
+            linthresh = t.linthresh
+            # Only compute the number of decades in the logarithmic part of the
+            # axis
+            numdec = 0
+            if vmin < -linthresh:
+                numdec += math.log(-vmin / linthresh) / math.log(b)
+
+            if vmax > linthresh and vmin < linthresh:
+                numdec += math.log(vmax / linthresh) / math.log(b)
+            elif vmin >= linthresh:
+                numdec += math.log(vmax / vmin) / math.log(b)
+        else:
+            vmin = math.log(vmin) / math.log(b)
+            vmax = math.log(vmax) / math.log(b)
+            numdec = abs(vmax - vmin)

        if numdec > 3:
            # Label only bases