title: Data size changes when training the model with tensorflow
body: <p>I'm trying to train a CNN on the "Cifar10" data set. I import it and when I check the shape:</p>
  
  <pre><code>cifar10 = tf.keras.datasets.cifar10
  (x_train, y_train), (x_test, y_test) = cifar10.load_data()
  x_train, x_test = x_train / 255.0, x_test / 255.0
  y_train, y_test = y_train.flatten(), y_test.flatten()
  print("x_train.shape:", x_train.shape)
  print("y_train.shape", y_train.shape)
  </code></pre>
  
  <p>And what I get is:</p>
  
  <pre><code>x_train.shape: (50000, 32, 32, 3)
  y_train.shape (50000,)
  </code></pre>
  
  <p>Which indicates my data has 50000 instances. However when training the model:</p>
  
  <pre><code>r = model.fit(x_train, y_train, epochs=2)
  </code></pre>
  
  <p>The log shows:</p>
  
  <pre><code>Epoch 1/2
  1563/1563 [==============================] - 7s 5ms/step - loss: 1.4601 - accuracy: 0.4819
  Epoch 2/2
  1563/1563 [==============================] - 7s 5ms/step - loss: 1.1266 - accuracy: 0.6025
  </code></pre>
  
  <p>Which is saying there are only 1563 instances. What could possibly cause this?</p>
  
  <p>The complete notebook is available <a href="https://colab.research.google.com/drive/1hR5IlAM9mDNgto8PeM1MqdYatmiLJM3q" rel="nofollow noreferrer">here</a></p>