ENH: Don't round degree digits when zoomed on PolarAxes.

QuLogic · QuLogic · commit 0b6cc581a4b4 · 2017-08-15T22:19:31.000-04:00
diff --git a/lib/matplotlib/projections/polar.py b/lib/matplotlib/projections/polar.py
@@ -173,15 +173,21 @@ 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 = np.rad2deg(abs(vmax - vmin))
+        digits = max(-int(np.log10(d) - 1.5), 0)
+
         if rcParams['text.usetex'] and not rcParams['text.latex.unicode']:
-            return r"$%0.0f^\circ$" % ((x / np.pi) * 180.0)
+            format_str = r"${value:0.{digits:d}f}^\circ$"
+            return format_str.format(value=np.rad2deg(x), digits=digits)
         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\N{DEGREE SIGN}" % ((x / np.pi) * 180.0)
+            format_str = "{value:0.{digits:d}f}\N{DEGREE SIGN}"
+            return format_str.format(value=np.rad2deg(x), digits=digits)
 
 
 class RadialLocator(Locator):
