FIX symlog scale now shows negative labels.

NelleV · NelleV · commit d52675fb23bf · 2016-10-24T11:24:31.000-04:00
The formatter returned empty strings for negative value. closes #7146
diff --git a/lib/matplotlib/tests/test_ticker.py b/lib/matplotlib/tests/test_ticker.py
@@ -1,8 +1,6 @@
 from __future__ import (absolute_import, division, print_function,
                         unicode_literals)
 
-import six
-
 from numpy.testing import assert_almost_equal
 import numpy as np
 import pytest
@@ -305,6 +303,7 @@ def test_LogFormatterExponent_blank():
 def test_LogFormatterSciNotation():
     test_cases = {
         10: (
+             (-1, '${-10^{0}}$'),
              (1e-05, '${10^{-5}}$'),
              (1, '${10^{0}}$'),
              (100000, '${10^{5}}$'),
diff --git a/lib/matplotlib/ticker.py b/lib/matplotlib/ticker.py
@@ -902,7 +902,7 @@ def __call__(self, x, pos=None):
         fx = math.log(abs(x)) / math.log(b)
         isDecade = is_close_to_int(fx)
         exponent = np.round(fx) if isDecade else np.floor(fx)
-        coeff = np.round(x / b ** exponent)
+        coeff = np.round(abs(x) / b ** exponent)
         if coeff in self.sublabel:
             if not isDecade and self.labelOnlyBase:
                 s = ''
@@ -1032,7 +1032,7 @@ def __call__(self, x, pos=None):
         fx = math.log(abs(x)) / math.log(b)
         is_decade = is_close_to_int(fx)
         exponent = np.round(fx) if is_decade else np.floor(fx)
-        coeff = np.round(x / b ** exponent)
+        coeff = np.round(abs(x) / b ** exponent)
 
         sign_string = '-' if x < 0 else ''
 
