update lesson28

Author: dragen1860

深度学习与TensorFlow入门实战-源码和PPT/lesson28-可视化/main.py

@@ -1,9 +1,14 @@
+import  os
+os.environ['TF_CPP_MIN_LOG_LEVEL']='2'
+
 import  tensorflow as tf
 from    tensorflow.keras import datasets, layers, optimizers, Sequential, metrics
 import  datetime
 from    matplotlib import pyplot as plt
 import  io
 
+assert tf.__version__.startswith('2.')
+
 def preprocess(x, y):
 
     x = tf.cast(x, dtype=tf.float32) / 255.