polar: Don't round all degree digits when zoomed.

QuLogic · QuLogic · commit bfc0b5ca85d7 · 2015-07-17T05:31:49.000-04:00
diff --git a/lib/matplotlib/projections/polar.py b/lib/matplotlib/projections/polar.py
@@ -173,16 +173,22 @@ class ThetaFormatter(Formatter):
     unit of radians into degrees and adds a degree symbol.
     """
     def __call__(self, x, pos=None):
+        vmin, vmax = self.axis.get_view_interval()
+        d = abs(vmax - vmin) / np.pi * 180.0
+        digits = max(-int(np.log10(d) - 1.5), 0)
+
         # \u00b0 : degree symbol
         if rcParams['text.usetex'] and not rcParams['text.latex.unicode']:
-            return r"$%0.0f^\circ$" % ((x / np.pi) * 180.0)
+            format_str = r"$%%0.%df^\circ$" % (digits, )
+            return format_str % ((x / np.pi) * 180.0)
         else:
             # we use unicode, rather than mathtext with \circ, so
             # that it will work correctly with any arbitrary font
             # (assuming it has a degree sign), whereas $5\circ$
             # will only work correctly with one of the supported
             # math fonts (Computer Modern and STIX)
-            return "%0.0f\u00b0" % ((x / np.pi) * 180.0)
+            format_str = "%%0.%df\u00b0" % (digits, )
+            return format_str % ((x / np.pi) * 180.0)
 
 
 class ThetaLocator(MaxNLocator):
