change numpy to bytearray as buffer

wrapper/xgboost.py

@@ -97,11 +97,12 @@ def ctypes2numpy(cptr, length, dtype):
 def ctypes2buffer(cptr, length):
     if not isinstance(cptr, ctypes.POINTER(ctypes.c_char)):
         raise RuntimeError('expected char pointer')
-    res = np.zeros(length, dtype='uint8')
-    if not ctypes.memmove(res.ctypes.data, cptr, length * res.strides[0]):
+    res = bytearray(length)
+    rptr = (ctypes.c_char * length).from_buffer(res)
+    if not ctypes.memmove(rptr, cptr, length):
         raise RuntimeError('memmove failed')
     return res
-        
+
 def c_str(string):
     return ctypes.c_char_p(string.encode('utf-8'))
 
@@ -886,7 +887,7 @@ def __getstate__(self):
     def __setstate__(self, state):
         bst = state["_Booster"]
         if bst is not None:
-            state["_Booster"] = Booster(model_file=booster)
+            state["_Booster"] = Booster(model_file=bst)
         self.__dict__.update(state)
 
     def booster(self):