refactor LogFormatter classes for consistency, readability

efiring · efiring · commit 8bdabcdb3e92 · 2016-12-11T13:21:31.000-10:00
diff --git a/lib/matplotlib/ticker.py b/lib/matplotlib/ticker.py
@@ -902,10 +902,6 @@ def set_locs(self, locs=None):
             self._sublabels = None
             return
 
-        b = self._base
-
-        vmin, vmax = self.axis.get_view_interval()
-
         # Handle symlog case:
         linthresh = self._linthresh
         if linthresh is None:
@@ -914,6 +910,7 @@ def set_locs(self, locs=None):
             except AttributeError:
                 pass
 
+        vmin, vmax = self.axis.get_view_interval()
         if vmin > vmax:
             vmin, vmax = vmax, vmin
 
@@ -924,6 +921,7 @@ def set_locs(self, locs=None):
             self._sublabels = set((1,))  # label powers of base
             return
 
+        b = self._base
         if linthresh is not None:  # symlog
             # Only compute the number of decades in the logarithmic part of the
             # axis
@@ -953,37 +951,38 @@ def set_locs(self, locs=None):
             # Label all integer multiples of base**n.
             self._sublabels = set(np.arange(1, b + 1))
 
+    def _num_to_string(self, x, vmin, vmax):
+        if x > 10000:
+            s = '%1.0e' % x
+        elif x < 1:
+            s = '%1.0e' % x
+        else:
+            s = self.pprint_val(x, vmax - vmin)
+
     def __call__(self, x, pos=None):
         """
         Return the format for tick val `x`.
         """
-        vmin, vmax = self.axis.get_view_interval()
-        vmin, vmax = mtransforms.nonsingular(vmin, vmax, expander=0.05)
-        d = abs(vmax - vmin)
-        b = self._base
         if x == 0.0:  # Symlog
             return '0'
+
         sign = np.sign(x)
         x = abs(x)
+        b = self._base
         # only label the decades
         fx = math.log(x) / math.log(b)
         is_x_decade = is_close_to_int(fx)
         exponent = np.round(fx) if is_x_decade else np.floor(fx)
         coeff = np.round(x / b ** exponent)
+
         if self.labelOnlyBase and not is_x_decade:
             return ''
         if self._sublabels is not None and coeff not in self._sublabels:
             return ''
 
-        if x > 10000:
-            s = '%1.0e' % x
-        elif x < 1:
-            s = '%1.0e' % x
-        else:
-            s = self.pprint_val(x, d)
-        if sign == -1:
-            s = '-%s' % s
-
+        vmin, vmax = self.axis.get_view_interval()
+        vmin, vmax = mtransforms.nonsingular(vmin, vmax, expander=0.05)
+        s = self._num_to_string(x, vmin, vmax)
         return self.fix_minus(s)
 
     def format_data(self, value):
@@ -1036,41 +1035,16 @@ class LogFormatterExponent(LogFormatter):
     """
     Format values for log axis using ``exponent = log_base(value)``.
     """
-    def __call__(self, x, pos=None):
-        """
-        Return the format for tick value `x`.
-        """
-        vmin, vmax = self.axis.get_view_interval()
-        vmin, vmax = mtransforms.nonsingular(vmin, vmax, expander=0.05)
-        d = abs(vmax - vmin)
-        b = self._base
-        if x == 0:
-            return '0'
-        sign = np.sign(x)
-        x = abs(x)
-        # only label the decades
-        fx = math.log(x) / math.log(b)
-
-        is_x_decade = is_close_to_int(fx)
-        exponent = np.round(fx) if is_x_decade else np.floor(fx)
-        coeff = np.round(x / b ** exponent)
-
-        if self.labelOnlyBase and not is_x_decade:
-            return ''
-        if self._sublabels is not None and coeff not in self._sublabels:
-            return ''
-
+    def _num_to_string(self, x, vmin, vmax):
+        fx = math.log(x) / math.log(self._base)
         if abs(fx) > 10000:
             s = '%1.0g' % fx
         elif abs(fx) < 1:
             s = '%1.0g' % fx
         else:
-            fd = math.log(abs(d)) / math.log(b)
+            fd = math.log(vmax - vmin) / math.log(self._base)
             s = self.pprint_val(fx, fd)
-        if sign == -1:
-            s = '-%s' % s
-
-        return self.fix_minus(s)
+        return s
 
 
 class LogFormatterMathtext(LogFormatter):
@@ -1092,35 +1066,34 @@ def __call__(self, x, pos=None):
 
         The position `pos` is ignored.
         """
-        b = self._base
         usetex = rcParams['text.usetex']
-
-        # only label the decades
-        if x == 0:
+        if x == 0:  # Symlog
             if usetex:
                 return '$0$'
             else:
                 return '$%s$' % _mathdefault('0')
 
         sign_string = '-' if x < 0 else ''
         x = abs(x)
+        b = self._base
 
+        # only label the decades
         fx = math.log(x) / math.log(b)
         is_x_decade = is_close_to_int(fx)
         exponent = np.round(fx) if is_x_decade else np.floor(fx)
         coeff = np.round(x / b ** exponent)
 
+        if self.labelOnlyBase and not is_x_decade:
+            return ''
+        if self._sublabels is not None and coeff not in self._sublabels:
+            return ''
+
         # use string formatting of the base if it is not an integer
         if b % 1 == 0.0:
             base = '%d' % b
         else:
             base = '%s' % b
 
-        if self.labelOnlyBase and not is_x_decade:
-            return ''
-        if self._sublabels is not None and coeff not in self._sublabels:
-            return ''
-
         if not is_x_decade:
             return self._non_decade_format(sign_string, base, fx, usetex)
         else:
