python - 使用 CNN 超参数优化进行多目标回归时出错

Question

我正在尝试使用 CNN 解决多目标回归问题。为了优化超参数，我使用了 Talos 库，但最终出现错误:

Error when checking input: expected conv1d_1_input to have 3 dimensions, but got array with shape (280000, 70)

数据集描述:X有70个特征，Y有32个目标时间序列长度:509760个时间点

Shape of Dataset:

Train Data size: (400000, 70),
Train Target size: (400000, 32),
Test Data size: (109760, 70),
Test Target size: (109760, 32),

代码:

tf.keras.backend.clear_session()

def model(x_train, y_train, x_val, y_val, params):

    n_timesteps, n_features, n_outputs = x_train.shape[0],    x_train.shape[1], y_train.shape[1]

    model = Sequential()

    model.add(Conv1D(filters=params['conv1_filter'], kernel_size=(3), activation=params['activation'], input_shape=(n_timesteps,n_features)))
    model.add(Conv1D(filters=params['conv2_filter'], kernel_size=(3), activation=params['activation']))
    model.add(MaxPooling1D(pool_size=2))
    model.add(Dropout(params['dropout']))
    model.add(Conv1D(filters=8, kernel_size=3, activation=params['activation']))
    model.add(MaxPooling1D(pool_size=2))
    model.add(Dense(100, activation=params['activation']))
    model.add(Dense(n_outputs))

    model.add(Flatten())    
    model.compile(loss='mse',optimizer=params['optimizer'](),metrics=['acc', fmeasure_acc])


    out = model.fit(x_train, y_train, validation_data=[x_val, y_val], batch_size=params['batch_size'], epochs=params['epochs'],verbose=1,shuffle=True)

    return out, model

p = {'conv1_filter':[32],
     'conv2_filter':[32],
     'optimizer': [Nadam],
     'batch_size': [1000],
     'epochs': [5],
     'dropout': [0.5],
     'activation':[relu]}

# and run the experiment
t = ta.Scan(x=x_train,y=y_train,model=model,params=p,experiment_no='1')

错误如下:

    168         # input parameters section ends
    169 
--> 170         self._null = self.runtime()
    171 
    172     def runtime(self):

/anaconda3/lib/python3.7/site-packages/talos/scan/Scan.py in runtime(self)
    173 
    174         self = scan_prepare(self)
--> 175         self = scan_run(self)

/anaconda3/lib/python3.7/site-packages/talos/scan/scan_run.py in scan_run(self)
     16                      disable=self.disable_progress_bar)
     17     while len(self.param_log) != 0:
---> 18         self = scan_round(self)
     19         self.pbar.update(1)
     20     self.pbar.close()

/anaconda3/lib/python3.7/site-packages/talos/scan/scan_round.py in scan_round(self)
     30     # fit the model
     31     try:
---> 32         _hr_out, self.keras_model = ingest_model(self)
     33     except TypeError as err:
     34         if err.args[0] == "unsupported operand type(s) for +: 'int' and 'numpy.str_'":

/anaconda3/lib/python3.7/site-packages/talos/model/ingest_model.py in ingest_model(self)
      8                       self.x_val,
      9                       self.y_val,
---> 10                       self.round_params)

<ipython-input-9-b33b869928ed> in model(x_train, y_train, x_val, y_val, params)
     20 
     21 
---> 22     out = model.fit(x_train, y_train, validation_data=[x_val, y_val], batch_size=params['batch_size'], epochs=params['epochs'],verbose=1,shuffle=True)
     23 
     24 

/anaconda3/lib/python3.7/site-packages/keras/engine/training.py in fit(self, x, y, batch_size, epochs, verbose, callbacks, validation_split, validation_data, shuffle, class_weight, sample_weight, initial_epoch, steps_per_epoch, validation_steps, **kwargs)
    950             sample_weight=sample_weight,
    951             class_weight=class_weight,
--> 952             batch_size=batch_size)
    953         # Prepare validation data.
    954         do_validation = False

/anaconda3/lib/python3.7/site-packages/keras/engine/training.py in _standardize_user_data(self, x, y, sample_weight, class_weight, check_array_lengths, batch_size)
    749             feed_input_shapes,
    750             check_batch_axis=False,  # Don't enforce the batch size.
--> 751             exception_prefix='input')
    752 
    753         if y is not None:

/anaconda3/lib/python3.7/site-packages/keras/engine/training_utils.py in standardize_input_data(data, names, shapes, check_batch_axis, exception_prefix)
    126                         ': expected ' + names[i] + ' to have ' +
    127                         str(len(shape)) + ' dimensions, but got array '
--> 128                         'with shape ' + str(data_shape))
    129                 if not check_batch_axis:
    130                     data_shape = data_shape[1:]

ValueError: Error when checking input: expected conv1d_1_input to have 3 dimensions, but got array with shape (280000, 70)

Answer 1

我又看了一遍，您的代码中需要更改一些内容。我测试了它，现在应该可以工作了:

首先，模型本身有几个问题。

也就是说，模型的输入应该是 (n_features, 1) 而不是 (n_timesteps,n_features)。 Keras 内部认为您在给出输入形状时忽略了批量维度。因此，当它将注册为形状时(batch_size, n_features, 1)。最后一个维度是必需的，以便与 Conv1D 兼容。

它应该是这样的:

model.add(Conv1D(filters=params['conv1_filter'], kernel_size=(3), activation=params['activation'], input_shape=(n_features, 1))) 

其次，模型不应以 Flatten() 层结束。相反，该层应该位于 Dense() 层之前(以便它看到 2D 输入而不是 3D 输入)。两次更改后，模型应如下所示:

model = Sequential()

model.add(Conv1D(filters=params['conv1_filter'], kernel_size=(3), activation=params['activation'], input_shape=(n_features,1))) 
model.add(Conv1D(filters=params['conv2_filter'], kernel_size=(3), activation=params['activation']))
model.add(MaxPooling1D(pool_size=2))
model.add(Dropout(params['dropout']))
model.add(Conv1D(filters=8, kernel_size=3, activation=params['activation']))
model.add(MaxPooling1D(pool_size=2))
model.add(Flatten())
model.add(Dense(100, activation=params['activation']))
model.add(Dense(n_outputs))

因为我们更改了模型的 input_shape，所以我们需要更改数据的形状。需要做的是将 (400000, 70) 更改为 (400000, 70, 1) 并将 (109760, 70) 更改为 (109760, 70, 1)。这可以通过以下命令来完成:

x_train = np.expand_dims(x_train, axis=-1)
x_val = np.expand_dims(x_val, axis=-1)

我没有在 Talos 上进行测试，但 keras 部分工作得很好。