some fix

examples/mnist-convnet.py

@@ -3,8 +3,8 @@
 # File: mnist-convnet.py
 # Author: Yuxin Wu <ppwwyyxx@gmail.com>
 
-import tensorflow as tf
 import numpy as np
+import tensorflow as tf
 import os, sys
 import argparse
 

tensorpack/__init__.py

@@ -2,6 +2,7 @@
 # File: __init__.py
 # Author: Yuxin Wu <ppwwyyxx@gmail.com>
 
+import numpy
 import cv2  # fix https://github.com/tensorflow/tensorflow/issues/1924
 from . import models
 from . import train

tensorpack/dataflow/dataset/atari.py

@@ -2,15 +2,20 @@
 # -*- coding: utf-8 -*-
 # File: atari.py
 # Author: Yuxin Wu <ppwwyyxxc@gmail.com>
-from ale_python_interface import ALEInterface
+
 import numpy as np
 import time
 import os
 import cv2
 from collections import deque
-from ...utils import get_rng
+from ...utils import get_rng, logger
 from .rlenv import RLEnvironment
 
+try:
+    from ale_python_interface import ALEInterface
+except ImportError:
+    logger.warn("Cannot import ale_python_interface, Atari won't be available.")
+
 __all__ = ['AtariDriver', 'AtariPlayer']
 
 class AtariDriver(object):