How to return history of validation loss in Keras

Using Anaconda Python 2.7 Windows 10.

I am training a language model using the Keras exmaple:

print('Build model...')
model = Sequential()
model.add(GRU(512, return_sequences=True, input_shape=(maxlen, len(chars))))
model.add(GRU(512, return_sequences=False))

model.compile(loss='categorical_crossentropy', optimizer='rmsprop')

def sample(a, temperature=1.0):
    # helper function to sample an index from a probability array
    a = np.log(a) / temperature
    a = np.exp(a) / np.sum(np.exp(a))
    return np.argmax(np.random.multinomial(1, a, 1))

# train the model, output generated text after each iteration
for iteration in range(1, 3):
    print('-' * 50)
    print('Iteration', iteration), y, batch_size=128, nb_epoch=1)
    start_index = random.randint(0, len(text) - maxlen - 1)

    for diversity in [0.2, 0.5, 1.0, 1.2]:
        print('----- diversity:', diversity)

        generated = ''
        sentence = text[start_index: start_index + maxlen]
        generated += sentence
        print('----- Generating with seed: "' + sentence + '"')

        for i in range(400):
            x = np.zeros((1, maxlen, len(chars)))
            for t, char in enumerate(sentence):
                x[0, t, char_indices[char]] = 1.

            preds = model.predict(x, verbose=0)[0]
            next_index = sample(preds, diversity)
            next_char = indices_char[next_index]

            generated += next_char
            sentence = sentence[1:] + next_char


According to Keras documentation, the method returns a History callback, which has a history attribute containing the lists of successive losses and other metrics.

hist =, y, validation_split=0.2)

After training my model, if I run print(model.history) I get the error:

 AttributeError: 'Sequential' object has no attribute 'history'

How do I return my model history after training my model with the above code?


The issue was that:

The following had to first be defined:

from keras.callbacks import History 
history = History()

The callbacks option had to be called, Y_train, nb_epoch=5, batch_size=16, callbacks=[history])

But now if I print


it returns


even though I ran an iteration.


It’s been solved.

The losses only save to the History over the epochs. I was running iterations instead of using the Keras built in epochs option.

so instead of doing 4 iterations I now have, nb_epoch = 4)

Now it returns the loss for each epoch run:

{'loss': [1.4358016599558268, 1.399221191623641, 1.381293383180471, h1.3758836857303727]}

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