Merge pull request #3409 from y-p/GH3360c

BUG: don't rely on sys.getdefaultencoding if we don't need to

Author: y-p

pandas/core/format.py

@@ -165,7 +165,9 @@ def _encode_diff_func():
         encoding = get_option("display.encoding")
 
         def _encode_diff(x):
-            return len(x) - len(x.decode(encoding))
+            if not isinstance(x,unicode):
+                return len(x) - len(x.decode(encoding))
+            return 0
 
     return _encode_diff
 
@@ -1639,13 +1641,14 @@ def reset_printoptions():
                   FutureWarning)
     reset_option("^display\.")
 
-
+_initial_defencoding = None
 def detect_console_encoding():
     """
     Try to find the most capable encoding supported by the console.
     slighly modified from the way IPython handles the same issue.
     """
     import locale
+    global _initial_defencoding
 
     encoding = None
     try:
@@ -1662,6 +1665,11 @@ def detect_console_encoding():
     if not encoding or 'ascii' in encoding.lower():  # when all else fails. this will usually be "ascii"
             encoding = sys.getdefaultencoding()
 
+    # GH3360, save the reported defencoding at import time
+    # MPL backends may change it. Make available for debugging.
+    if not _initial_defencoding:
+        _initial_defencoding = sys.getdefaultencoding()
+
     return encoding