BaseCollectiveExecutor :: StartAbort Неверный аргумент: индексы [0,25] = -1 не в [0, 400000)

Question

Я пытаюсь предсказать следующее слово с CBOW. Вот модель. Ошибка происходит на шаге model.predict

model = Sequential()
model.add(Embedding(input_dim=num_embeddings, output_dim=embedding_dim, weights=[pretrained_weights]))
model.add(Lambda(lambda x: K.mean(x, axis=1), output_shape=(embedding_dim,)))
model.add(Dense(embedding_dim, activation='softmax'))

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

def generate_next(text, num_generated=10):
    print(type(text))
    print('Generating the next...')
    pred_weights = np.zeros([len(text.split()), 50])

    for t, word in enumerate(text.split()):
        print(word)
        pred_weights[t] = word2idx(word.lower())

    for i in range(num_generated):
        prediction = model.predict(x=pred_weights)
        idx = sample(prediction[-1], temperature=0.7)
        pred_weights.append(idx)

    return ' '.join(idx2word(idx) for idx in word_idxs)

Ошибка:

2020-03-14 14:28:43.748512: W tensorflow/core/common_runtime/base_collective_executor.cc:217] BaseCollectiveExecutor::StartAbort Invalid argument: indices[0,25] = -1 is not in [0, 400000)
     [[{{node embedding_1/embedding_lookup}}]]
Traceback (most recent call last):
  File "cbow.py", line 107, in <module>
    sample = generate_next(text)
  File "cbow.py", line 91, in generate_next
    prediction = model.predict(x=pred_weights)
  File "/home/guzel/Anaconda3-2019.10/lib/python3.7/site-packages/keras/engine/training.py", line 1462, in predict
    callbacks=callbacks)
  File "/home/guzel/Anaconda3-2019.10/lib/python3.7/site-packages/keras/engine/training_arrays.py", line 324, in predict_loop
    batch_outs = f(ins_batch)
  File "/home/guzel/Anaconda3-2019.10/lib/python3.7/site-packages/tensorflow_core/python/keras/backend.py", line 3727, in __call__
    outputs = self._graph_fn(*converted_inputs)
  File "/home/guzel/Anaconda3-2019.10/lib/python3.7/site-packages/tensorflow_core/python/eager/function.py", line 1551, in __call__
    return self._call_impl(args, kwargs)
  File "/home/guzel/Anaconda3-2019.10/lib/python3.7/site-packages/tensorflow_core/python/eager/function.py", line 1591, in _call_impl
    return self._call_flat(args, self.captured_inputs, cancellation_manager)
  File "/home/guzel/Anaconda3-2019.10/lib/python3.7/site-packages/tensorflow_core/python/eager/function.py", line 1692, in _call_flat
    ctx, args, cancellation_manager=cancellation_manager))
  File "/home/guzel/Anaconda3-2019.10/lib/python3.7/site-packages/tensorflow_core/python/eager/function.py", line 545, in call
    ctx=ctx)
  File "/home/guzel/Anaconda3-2019.10/lib/python3.7/site-packages/tensorflow_core/python/eager/execute.py", line 67, in quick_execute
    six.raise_from(core._status_to_exception(e.code, message), None)
  File "<string>", line 3, in raise_from
tensorflow.python.framework.errors_impl.InvalidArgumentError:  indices[0,25] = -1 is not in [0, 400000)
     [[node embedding_1/embedding_lookup (defined at /home/guzel/Anaconda3-2019.10/lib/python3.7/site-packages/keras/backend/tensorflow_backend.py:3009) ]] [Op:__inference_keras_scratch_graph_126]

Function call stack:
keras_scratch_graph

pretrained_weights.shape is (400000,50) - используется для встраивания слоя

pred_weights.shape is (6,50) - входные данные

Возможно, причина здесь:

print(np.where(pretrained_weights == -2))

дает

(array([ 18807,  56773,  68753, 116154, 117857, 122205, 151525, 176865,
       218782, 235726, 266661, 271962, 272754, 313663, 326581, 342410,
       353057, 372100, 391140]), array([16, 13, 16, 34, 26, 13, 41, 30, 28, 30, 30, 45, 30,  1, 34, 30, 30,
       30, 30]))

Но

print(np.where(pred_weights == -2))

т

(array([], dtype=int64), array([], dtype=int64))