可以使用以下3种方式构建模型:使用Sequential按层顺序构建模型,使用函数式API构建任意结构模型,继承Model基类构建自定义模型。
对于顺序结构的模型,优先使用Sequential方法构建。
如果模型有多输入或者多输出,或者模型需要共享权重,或者模型具有残差连接等非顺序结构,推荐使用函数式API进行创建。
如果无特定必要,尽可能避免使用Model子类化的方式构建模型,这种方式提供了极大的灵活性,但也有更大的概率出错。
下面以IMDB电影评论的分类问题为例,演示3种创建模型的方法。
@H_301_11@import numpy as np
pandas as pd
tensorflow as tf
from tqdm tqdm
from tensorflow.keras import *
train_token_path = "./data/imdb/train_token.csv"
test_token_path = ./data/imdb/test_token.csv
MAX_WORDS = 10000 # We will only consider the top 10,000 words in the dataset
MAX_LEN = 200 We will cut reviews after 200 words
BATCH_SIZE = 20
构建管道
def parse_line(line):
t = tf.strings.split(line,\t)
label = tf.reshape(tf.cast(tf.strings.to_number(t[0]),tf.int32),(-1,))
features = tf.cast(tf.strings.to_number(tf.strings.split(t[1],1)">" )),tf.int32)
return (features,label)
ds_train= tf.data.TextLineDataset(filenames = [train_token_path]) \
.map(parse_line,num_parallel_calls = tf.data.experimental.AUTOTUNE) \
.shuffle(buffer_size = 1000).batch(BATCH_SIZE) \
.prefetch(tf.data.experimental.AUTOTUNE)
ds_test= tf.data.TextLineDataset(filenames = [test_token_path]) \
.map(parse_line,1)">).batch(BATCH_SIZE) \
.prefetch(tf.data.experimental.AUTOTUNE)
一,Sequential按层顺序创建模型
@H_301_11@f.keras.backend.clear_session()
model = models.Sequential()
model.add(layers.Embedding(MAX_WORDS,7,input_length=MAX_LEN))
model.add(layers.Conv1D(filters = 64,kernel_size = 5,activation = relu))
model.add(layers.MaxPool1D(2))
model.add(layers.Conv1D(filters = 32,kernel_size = 3,1)">))
model.add(layers.Flatten())
model.add(layers.Dense(1,1)">sigmoid))
model.compile(optimizer='Nadam'binary_crossentropyaccuracy',1)">AUC])
model.summary()
@H_301_11@Model: sequential"
_________________________________________________________________
Layer (type) Output Shape Param #
=================================================================
embedding (Embedding) (None,200,7) 70000
conv1d (Conv1D) (None,196,64) 2304
max_pooling1d (MaxPooling1D) (None,98,64) 0
conv1d_1 (Conv1D) (None,96,32) 6176
max_pooling1d_1 (MaxPooling1 (None,48,32
flatten (Flatten) (None,1536) 0
dense (Dense) (None,1) 1537
=================================================================
Total params: 80,017
Trainable params: 80,1)">
Non-trainable params: 0
_________________________________________________________________
@H_301_11@ datetime
baselogger = callbacks.BaseLogger(stateful_metrics=[auc])
logdir = ./data/keras_model/" + datetime.datetime.now().strftime(%Y%m%d-%H%M%S)
tensorboard_callback = tf.keras.callbacks.TensorBoard(logdir,histogram_freq=1)
history = model.fit(ds_train,validation_data = ds_test,epochs = 6,callbacks=[baselogger,tensorboard_callback])
%matplotlib inline
%config InlineBackend.figure_format = svg'
matplotlib.pyplot as plt
plot_metric(history,metric):
train_metrics = history.history[metric]
val_metrics = history.history[val_'+metric]
epochs = range(1,len(train_metrics) + 1)
plt.plot(epochs,train_metrics,bo--ro-)
plt.title(Training and validation metric)
plt.xlabel(Epochs)
plt.ylabel(metric)
plt.legend([train_"+metric,1)">metric])
plt.show()
plot_metric(history,1)">"auc")
这里不能成功运行。。。,错误如下:
@H_301_11@Epoch 1/6
1000/Unknown - 17s 17ms/step - loss: 0.1133 - accuracy: 0.9588 - auc: 0.9918
---------------------------------------------------------------------------
KeyError Traceback (most recent call last)
<ipython-input-17-8cd49fdfb6d8> in <module>()
4 tensorboard_callback = tf.keras.callbacks.TensorBoard(logdir,1)">)
5 history = model.fit(ds_train,----> 6 epochs = 6,tensorboard_callback])
7 """
8 %matplotlib inline
3 frames
/usr/local/lib/python3.6/dist-packages/tensorflow/python/keras/callbacks.py in on_epoch_end(self,epoch,logs)
795 def on_epoch_end(self,logs=None):
796 if logs is not None:
--> 797 for k in self.params['metrics']:
798 if k in self.totals:
799 # Make value available to next callbacks.
KeyError: 'metrics'
只好先换成这样的:
@H_301_11@ datetime
logdir =
@H_301_11@Epoch 1/6
1000/1000 [==============================] - 44s 44ms/step - loss: 0.0058 - accuracy: 0.9980 - auc: 0.9999 - val_loss: 1.5239 - val_accuracy: 0.8598 - val_auc: 0.8961
Epoch 2/6
1000/1000 [==============================] - 44s 44ms/step - loss: 0.0011 - accuracy: 0.9996 - auc: 1.0000 - val_loss: 1.7804 - val_accuracy: 0.8610 - val_auc: 0.8920
Epoch 3/6
1000/1000 [==============================] - 44s 44ms/step - loss: 0.0034 - accuracy: 0.9990 - auc: 0.9999 - val_loss: 1.8452 - val_accuracy: 0.8524 - val_auc: 0.8861
Epoch 4/6
1000/1000 [==============================] - 43s 43ms/step - loss: 0.0107 - accuracy: 0.9969 - auc: 0.9995 - val_loss: 1.6515 - val_accuracy: 0.8582 - val_auc: 0.8901
Epoch 5/6
1000/1000 [==============================] - 44s 44ms/step - loss: 0.0022 - accuracy: 0.9994 - auc: 1.0000 - val_loss: 1.7680 - val_accuracy: 0.8522 - val_auc: 0.8864
Epoch 6/6
1000/1000 [==============================] - 44s 44ms/step - loss: 0.0052 - accuracy: 0.9979 - auc: 0.9999 - val_loss: 1.7506 - val_accuracy: 0.8554 - val_auc: 0.8918
二,函数式API创建任意结构模型
@H_301_11@tf.keras.backend.clear_session()
inputs = layers.Input(shape=[MAX_LEN])
x = layers.Embedding(MAX_WORDS,7)(inputs)
branch1 = layers.SeparableConv1D(64,3,activation=)(x)
branch1 = layers.MaxPool1D(3)(branch1)
branch1 = layers.SeparableConv1D(32,1)">)(branch1)
branch1 = layers.GlobalMaxPool1D()(branch1)
branch2 = layers.SeparableConv1D(64,5,1)">)(x)
branch2 = layers.MaxPool1D(5)(branch2)
branch2 = layers.SeparableConv1D(32,1)">)(branch2)
branch2 = layers.GlobalMaxPool1D()(branch2)
branch3 = layers.SeparableConv1D(64,7,1)">)(x)
branch3 = layers.MaxPool1D(7)(branch3)
branch3 = layers.SeparableConv1D(32,1)">)(branch3)
branch3 = layers.GlobalMaxPool1D()(branch3)
concat = layers.Concatenate()([branch1,branch2,branch3])
outputs = layers.Dense(1,1)">)(concat)
model = models.Model(inputs = inputs,outputs = outputs)
model.compile(optimizer=model__________________________________________________________________________________________________
Layer (type) Output Shape Param Connected to
==================================================================================================
input_1 (InputLayer) [(None,200)] 0
embedding (Embedding) (None,7) 70000 input_1[0][0]
separable_conv1d (SeparableConv (None,198,64) 533 embedding[0][0]
separable_conv1d_2 (SeparableCo (None,64) 547
separable_conv1d_4 (SeparableCo (None,194,64) 561
max_pooling1d (MaxPooling1D) (None,66,1)">) 0 separable_conv1d[0][0]
max_pooling1d_1 (MaxPooling1D) (None,39,1)">) 0 separable_conv1d_2[0][0]
max_pooling1d_2 (MaxPooling1D) (None,27,1)">) 0 separable_conv1d_4[0][0]
separable_conv1d_1 (SeparableCo (None,64,32) 2272 max_pooling1d[0][0]
separable_conv1d_3 (SeparableCo (None,35,32) 2400 max_pooling1d_1[0][0]
separable_conv1d_5 (SeparableCo (None,21,32) 2528 max_pooling1d_2[0][0]
global_max_pooling1d (GlobalMax (None,32) 0 separable_conv1d_1[0][0]
global_max_pooling1d_1 (GlobalM (None,1)">) 0 separable_conv1d_3[0][0]
global_max_pooling1d_2 (GlobalM (None,1)">) 0 separable_conv1d_5[0][0]
concatenate (Concatenate) (None,96) 0 global_max_pooling1d[0][0]
global_max_pooling1d_1[0][0]
global_max_pooling1d_2[0][0]
dense (Dense) (None,1) 97 concatenate[0][0]
==================================================================================================
Total params: 78,938
Trainable params: 78,1)">__________________________________________________________________________________________________
@H_301_11@
@H_301_11@Epoch 1/6
1000/1000 [==============================] - 28s 28ms/step - loss: 0.5210 - accuracy: 0.7120 - auc: 0.8098 - val_loss: 0.3512 - val_accuracy: 0.8482 - val_auc: 0.9254
Epoch 2/6
1000/1000 [==============================] - 27s 27ms/step - loss: 0.2842 - accuracy: 0.8805 - auc: 0.9510 - val_loss: 0.3302 - val_accuracy: 0.8588 - val_auc: 0.9384
Epoch 3/6
1000/1000 [==============================] - 27s 27ms/step - loss: 0.1931 - accuracy: 0.9265 - auc: 0.9772 - val_loss: 0.3955 - val_accuracy: 0.8512 - val_auc: 0.9336
Epoch 4/6
1000/1000 [==============================] - 27s 27ms/step - loss: 0.1203 - accuracy: 0.9594 - auc: 0.9906 - val_loss: 0.4669 - val_accuracy: 0.8494 - val_auc: 0.9273
Epoch 5/6
1000/1000 [==============================] - 27s 27ms/step - loss: 0.0664 - accuracy: 0.9798 - auc: 0.9965 - val_loss: 0.5963 - val_accuracy: 0.8476 - val_auc: 0.9158
Epoch 6/6
1000/1000 [==============================] - 27s 27ms/step - loss: 0.0305 - accuracy: 0.9934 - auc: 0.9987 - val_loss: 0.7246 - val_accuracy: 0.8440 - val_auc: 0.9063
@H_301_11@plot_metric(history,1)">")
三,Model子类化创建自定义模型
@H_301_11@ 先自定义一个残差模块,为自定义Layer
class ResBlock(layers.Layer):
def __init__(self,kernel_size,**kwargs):
super(ResBlock,self).__init__(**kwargs)
self.kernel_size = kernel_size
build(self,input_shape):
self.conv1 = layers.Conv1D(filters=64,kernel_size=self.kernel_size,activation = ",padding=same)
self.conv2 = layers.Conv1D(filters=32,1)">)
self.conv3 = layers.Conv1D(filters=input_shape[-1],kernel_size=self.kernel_size,1)">)
self.maxpool = layers.MaxPool1D(2)
super(ResBlock,self).build(input_shape) 相当于设置self.built = True
call(self,inputs):
x = self.conv1(inputs)
x = self.conv2(x)
x = self.conv3(x)
x = layers.Add()([inputs,x])
x = self.maxpool(x)
x
如果要让自定义的Layer通过Functional API 组合成模型时可以序列化,需要自定义get_config方法。
get_config(self):
config = super(ResBlock,self).get_config()
config.update({kernel_size: self.kernel_size})
config
测试ResBlock
resblock = ResBlock(kernel_size = 3)
resblock.build(input_shape = (None,200,1)">))
resblock.compute_output_shape(input_shape=(None,1)">))
自定义模型,实际上也可以使用Sequential或者FunctionalAPI
ImdbModel(models.Model):
__init__(self):
super(ImdbModel,1)">()
)
self.block1 = ResBlock(7)
self.block2 = ResBlock(5)
self.dense = layers.Dense(1,1)">)
super(ImdbModel,self).build(input_shape)
self.embedding(x)
x = self.block1(x)
x = self.block2(x)
x = layers.Flatten()(x)
x = self.dense(x)
(x)
tf.keras.backend.clear_session()
model = ImdbModel()
model.build(input_shape =(None,200))
model.summary()
model.compile(optimizer=])
datetime
logdir = ./tflogs/keras_model/[tensorboard_callback])
plot_metric(history,1)">")
@H_301_11@odel: imdb_model
embedding (Embedding) multiple 70000
res_block (ResBlock) multiple 19143
res_block_1 (ResBlock) multiple 13703
dense (Dense) multiple 351
=================================================================
Total params: 103,197
Trainable params: 103,1)">
Epoch 1/6
1000/1000 [==============================] - 44s 44ms/step - loss: 0.5311 - accuracy: 0.6953 - auc: 0.7931 - val_loss: 0.3333 - val_accuracy: 0.8522 - val_auc: 0.9352
Epoch 2/6
1000/1000 [==============================] - 43s 43ms/step - loss: 0.2507 - accuracy: 0.8985 - auc: 0.9619 - val_loss: 0.3906 - val_accuracy: 0.8404 - val_auc: 0.9427
Epoch 3/6
1000/1000 [==============================] - 43s 43ms/step - loss: 0.1448 - accuracy: 0.9465 - auc: 0.9868 - val_loss: 0.3965 - val_accuracy: 0.8742 - val_auc: 0.9403
Epoch 4/6
1000/1000 [==============================] - 43s 43ms/step - loss: 0.0758 - accuracy: 0.9745 - auc: 0.9958 - val_loss: 0.5496 - val_accuracy: 0.8648 - val_auc: 0.9279
Epoch 5/6
1000/1000 [==============================] - 43s 43ms/step - loss: 0.0296 - accuracy: 0.9898 - auc: 0.9990 - val_loss: 0.8675 - val_accuracy: 0.8592 - val_auc: 0.9111
Epoch 6/6
1000/1000 [==============================] - 43s 43ms/step - loss: 0.0208 - accuracy: 0.9927 - auc: 0.9995 - val_loss: 0.9153 - val_accuracy: 0.8578 - val_auc: 0.9094
参考:
开源电子书地址:https://lyhue1991.github.io/eat_tensorflow2_in_30_days/
GitHub 项目地址:https://github.com/lyhue1991/eat_tensorflow2_in_30_days