1 files changed, 16 insertions, 6 deletions
diff --git a/numpy/lib/function_base.py b/numpy/lib/function_base.py
index f76bf2a78..3d7428e69 100644
--- a/numpy/lib/function_base.py
+++ b/numpy/lib/function_base.py
@@ -1435,15 +1435,25 @@ def _nanop(op, fill, a, axis=None):
         Processed data.
 
     """
-    y = array(a,subok=True)
+    y = array(a, subok=True)
     mask = isnan(a)
-    if mask.all():
-        return np.nan
 
-    if not issubclass(y.dtype.type, np.integer):
-        y[mask] = fill
+    # We only need to take care of NaN's in floating point arrays
+    if not np.issubdtype(y.dtype, int):
+       y[mask] = fill
 
-    return op(y, axis=axis)
+    res = op(y, axis=axis)
+    mask_all_along_axis = mask.all(axis=axis)
+
+    # Along some axes, only nan's were encountered.  As such, any values
+    # calculated along that axis should be set to nan.
+    if mask_all_along_axis.any():
+        if np.isscalar(res):
+            res = np.nan
+        else:
+            res[mask_all_along_axis] = np.nan
+
+    return res
 
 def nansum(a, axis=None):
     """