title: how to plot training error and validation error vs number of epochs?
body: <p>how to plot training error and validation error vs number of epochs?</p>
  
  <pre><code>
  train_data = generate_arrays_for_training(indexPat, filesPath, end=75)
  validation_data=generate_arrays_for_training(indexPat, filesPath, start=75)
              model.fit_generator(generate_arrays_for_training(indexPat, filesPath, end=75), #end=75),#It take the first 75%
                                  validation_data=generate_arrays_for_training(indexPat, filesPath, start=75),#start=75), #It take the last 25%
                                  #steps_per_epoch=10000, epochs=10)
                                  steps_per_epoch=int((len(filesPath)-int(len(filesPath)/100*25))),#*25), 
                                  validation_steps=int((len(filesPath)-int(len(filesPath)/100*75))),#*75),
                                  verbose=2,
                                  epochs=300, max_queue_size=2, shuffle=True, callbacks=[callback])
  </code></pre>