title: Model fitting doesn't use all of the provided data
body: <p>I ran into a problem when playing with the introduction Tutorial for Tensorflow 2.0 Keras (<a href="https://www.tensorflow.org/tutorials/keras/classification" rel="nofollow noreferrer">https://www.tensorflow.org/tutorials/keras/classification</a>).</p>
  
  <p><strong>The Problem:</strong></p>
  
  <p>There should be (and there are) 60.000 Images to fit the model. I checked this by printing out the length of <code>train_images</code> and <code>train_labels</code>.</p>
  
  <p>The output when fitting the model on the other hand lets me believe that not all of the data was used as it says 1875/1875. Same for the Testing Data.</p>
  
  <p><em>I deactivated the GPU Detection which does not have an effect on this (so it seems).</em></p>
  
  <p>I'm using:</p>
  
  <ul>
  <li>Python 3.8.3</li>
  <li>Tensorflow 2.2.0</li>
  </ul>
  
  <p><strong>My Code:</strong></p>
  
  <pre><code>import tensorflow as tf
  from tensorflow import keras
  import numpy as np
  import matplotlib.pyplot as plt
  
  data = keras.datasets.fashion_mnist
  
  (train_images, train_labels), (test_images, test_labels) = data.load_data()
  
  class_names = ['T-shirt/top', 'Trouser', 'Pullover', 'Dress', 'Coat',
                 'Sandal', 'Shirt', 'Sneaker', 'Bag', 'Ankle boot']
  
  # preprocess the image data to have a pixel value between 0 and 1
  train_images = train_images / 255.0
  test_images = test_images / 255.0
  
  model = keras.Sequential([
      keras.layers.Flatten(input_shape=(28, 28)),
      keras.layers.Dense(128, activation='relu'),
      keras.layers.Dense(10)
  ])
  
  model.compile(optimizer='adam',
                loss=tf.keras.losses.SparseCategoricalCrossentropy(from_logits=True),
                metrics=['accuracy'])
  
  model.fit(train_images, train_labels, epochs=10)
  
  test_loss, test_acc = model.evaluate(test_images,  test_labels, verbose=2)
  
  print('\nTest accuracy:', test_acc)
  </code></pre>
  
  <p><strong>Output:</strong></p>
  
  <pre><code>2020-05-17 17:48:07.147033: I tensorflow/stream_executor/platform/default/dso_loader.cc:44] Successfully opened dynamic library cudart64_101.dll
  2020-05-17 17:48:10.075816: I tensorflow/stream_executor/platform/default/dso_loader.cc:44] Successfully opened dynamic library nvcuda.dll
  2020-05-17 17:48:10.098581: E tensorflow/stream_executor/cuda/cuda_driver.cc:313] failed call to cuInit: CUDA_ERROR_NO_DEVICE: no CUDA-capable device is detected
  2020-05-17 17:48:10.105898: I tensorflow/stream_executor/cuda/cuda_diagnostics.cc:169] retrieving CUDA diagnostic information for host: DESKTOP-UU9P1OG
  2020-05-17 17:48:10.109837: I tensorflow/stream_executor/cuda/cuda_diagnostics.cc:176] hostname: DESKTOP-UU9P1OG
  2020-05-17 17:48:10.113879: I tensorflow/core/platform/cpu_feature_guard.cc:143] Your CPU supports instructions that this TensorFlow binary was not compiled to use: AVX2
  2020-05-17 17:48:10.127711: I tensorflow/compiler/xla/service/service.cc:168] XLA service 0x14dc97288a0 initialized for platform Host (this does not guarantee that XLA will be used). Devices:
  2020-05-17 17:48:10.132743: I tensorflow/compiler/xla/service/service.cc:176]   StreamExecutor device (0): Host, Default Version
  Epoch 1/10
  1875/1875 [==============================] - 2s 1ms/step - loss: 0.4943 - accuracy: 0.8264
  Epoch 2/10
  1875/1875 [==============================] - 2s 938us/step - loss: 0.3747 - accuracy: 0.8649
  Epoch 3/10
  1875/1875 [==============================] - 2s 929us/step - loss: 0.3403 - accuracy: 0.8762
  Epoch 4/10
  1875/1875 [==============================] - 2s 914us/step - loss: 0.3146 - accuracy: 0.8844
  Epoch 5/10
  1875/1875 [==============================] - 2s 937us/step - loss: 0.2985 - accuracy: 0.8900
  Epoch 6/10
  1875/1875 [==============================] - 2s 923us/step - loss: 0.2808 - accuracy: 0.8964
  Epoch 7/10
  1875/1875 [==============================] - 2s 939us/step - loss: 0.2702 - accuracy: 0.8998
  Epoch 8/10
  1875/1875 [==============================] - 2s 911us/step - loss: 0.2585 - accuracy: 0.9032
  Epoch 9/10
  1875/1875 [==============================] - 2s 918us/step - loss: 0.2482 - accuracy: 0.9073
  Epoch 10/10
  1875/1875 [==============================] - 2s 931us/step - loss: 0.2412 - accuracy: 0.9106
  313/313 - 0s - loss: 0.3484 - accuracy: 0.8729
  
  Test accuracy: 0.8729000091552734
  </code></pre>