BUG: Check scale for AutoMinorLocator and throw a warning if not linear

cimarronm · cimarronm · commit cb5042d71c4d · 2015-12-16T16:04:37.000-08:00
diff --git a/lib/matplotlib/ticker.py b/lib/matplotlib/ticker.py
@@ -1924,8 +1924,7 @@ def __init__(self):
 class AutoMinorLocator(Locator):
     """
     Dynamically find minor tick positions based on the positions of
-    major ticks. Assumes the scale is linear and major ticks are
-    evenly spaced.
+    major ticks. The scale must be linear with major ticks evenly spaced.
     """
     def __init__(self, n=None):
         """
@@ -1939,6 +1938,10 @@ def __init__(self, n=None):
 
     def __call__(self):
         'Return the locations of the ticks'
+        if self.axis.get_scale() != 'linear':
+            warnings.warn('AutoMinorLocator only works with linear scale')
+            return []
+
         majorlocs = self.axis.get_majorticklocs()
         try:
             majorstep = majorlocs[1] - majorlocs[0]
