Fix numpy array check logic

python-package/xgboost/core.py

@@ -220,7 +220,7 @@ class DMatrix(object):
             self._init_from_csr(data)
         elif isinstance(data, scipy.sparse.csc_matrix):
             self._init_from_csc(data)
-        elif isinstance(data, np.ndarray) and len(data.shape) == 2:
+        elif isinstance(data, np.ndarray):
             self._init_from_npy2d(data, missing)
         else:
             try:
@@ -278,6 +278,8 @@ class DMatrix(object):
         """
         Initialize data from a 2-D numpy matrix.
         """
+        if len(mat.shape) != 2:
+            raise ValueError('Input numpy.ndarray must be 2 dimensional')
         data = np.array(mat.reshape(mat.size), dtype=np.float32)
         self.handle = ctypes.c_void_p()
         _check_call(_LIB.XGDMatrixCreateFromMat(data.ctypes.data_as(ctypes.POINTER(ctypes.c_float)),
@@ -792,11 +794,11 @@ class Booster(object):
         fname : string or a memory buffer
             Input file name or memory buffer(see also save_raw)
         """
-        if isinstance(fname, str):  # assume file name
+        if isinstance(fname, STRING_TYPES):  # assume file name
             if os.path.exists(fname):
                 _LIB.XGBoosterLoadModel(self.handle, c_str(fname))
             else:
-                raise ValueError("No such file: {0}")
+                raise ValueError("No such file: {0}".format(fname))
         else:
             buf = fname
             length = ctypes.c_ulong(len(buf))
@@ -851,6 +853,8 @@ class Booster(object):
                                                             ctypes.byref(length),
                                                             ctypes.byref(sarr)))
         else:
+            if fmap != '' and not os.path.exists(fmap):
+                raise ValueError("No such file: {0}".format(fmap))
             _check_call(_LIB.XGBoosterDumpModel(self.handle,
                                                 c_str(fmap),
                                                 int(with_stats),