Clean mnist reader

python/paddle/v2/data_set/mnist.py

@@ -15,39 +15,24 @@ def __mnist_reader_creator__(data, target):
     return reader
 
 
-class MNIST(object):
-    """
-    mnist dataset reader. The `train_reader` and `test_reader` method returns
-    a iterator of each sample. Each sample is combined by 784-dim float and a
-    one-dim label
-    """
-
-    def __init__(self, random_state=0, test_size=10000, **options):
-        data = sklearn.datasets.mldata.fetch_mldata(
+TEST_SIZE = 10000
+
+data = sklearn.datasets.mldata.fetch_mldata(
     "MNIST original", data_home=DATA_HOME)
-        self.X_train, self.X_test, self.y_train, self.y_test = sklearn.model_selection.train_test_split(
-            data.data,
-            data.target,
-            test_size=test_size,
-            random_state=random_state,
-            **options)
+X_train, X_test, y_train, y_test = sklearn.model_selection.train_test_split(
+    data.data, data.target, test_size=TEST_SIZE, random_state=0)
 
-    def train_creator(self):
-        return __mnist_reader_creator__(self.X_train, self.y_train)
 
-    def test_creator(self):
-        return __mnist_reader_creator__(self.X_test, self.y_test)
+def train_creator():
+    return __mnist_reader_creator__(X_train, y_train)
 
 
-__default_instance__ = MNIST()
-train_creator = __default_instance__.train_creator
-test_creator = __default_instance__.test_creator
+def test_creator():
+    return __mnist_reader_creator__(X_test, y_test)
 
 
 def unittest():
-    size = 12045
-    mnist = MNIST(test_size=size)
-    assert len(list(mnist.test_creator()())) == size
+    assert len(list(test_creator()())) == TEST_SIZE
 
 
 if __name__ == '__main__':