Merge pull request #2194 from minrk/clean_nan

Clean nan/inf in json_clean.

The floating point values NaN and Infinity are not part of the JSON
specification and causes some parsers to throw errors. Since our
usage is only for things like the display of function defaults, we
can use a basic string representation ('NaN', 'inf', etc) instead.

IPython/utils/jsonutil.py

@@ -11,6 +11,7 b''
 # Imports
 #-----------------------------------------------------------------------------
 # stdlib
+import math
 import re
 import sys
 import types
@@ -161,11 +162,17 b' def json_clean(obj):'
     """
     # types that are 'atomic' and ok in json as-is.  bool doesn't need to be
     # listed explicitly because bools pass as int instances
-    atomic_ok = (unicode, int, float, types.NoneType)
+    atomic_ok = (unicode, int, types.NoneType)
     
     # containers that we need to convert into lists
     container_to_list = (tuple, set, types.GeneratorType)
     
+    if isinstance(obj, float):
+        # cast out-of-range floats to their reprs
+        if math.isnan(obj) or math.isinf(obj):
+            return repr(obj)
+        return obj
+    
     if isinstance(obj, atomic_ok):
         return obj