在Keras中使用fit_generator时，我将验证集分为多个小批，并且每个小批都会随着训练的进行进行评估。我希望验证数据在每个时期结束时仅使用一次。也就是说，我的代码当前为：
def model_fit_generator(self):
#This does the actual training of the model
earlystop = EarlyStopping(monitor='val_acc', patience=5, verbose=2, mode='auto')
self.__model.fit_generator(generator=self.train_generator,
validation_data=self.valid_generator,
steps_per_epoch=self.s_per_e,
epochs=self.epochs,
validation_steps = self.v_per_e,
shuffle=False,
verbose=2,
callbacks=[earlystop])
model_filename = '_'.join([str(x) for x in now_list]) + '_model.h5'
self.__model.save(model_filename)
def model_evaluate(self):
self.model_fit_generator()
evaluation = self.__model.evaluate_generator(self.valid_generator, self.v_per_e, verbose=0)
return evaluation
如何更改此设置，以便在每个时期结束时使用一次验证数据来确定提前停止是否有用？
编辑：响应评论，这是一个完整的MWE，显示验证数据与训练数据同时使用。请注意，此代码将产生错误，但同时也会打印出批号，以表明同时使用了验证和训练集。要运行此代码，您将需要10个CSV数据文件，我可以提供这些数据，但我只想在此代码后立即为您提供输出。
from __future__ import division
from __future__ import print_function
from pandas import concat
from pandas import DataFrame
import sys, keras, GPy, GPyOpt
import numpy as np
import pandas as pd
from keras import backend as K
from keras.models import Model
from keras.metrics import binary_crossentropy
from keras.layers import Dense, Input, LSTM, Lambda
from keras.optimizers import Adam
from keras.callbacks import EarlyStopping
class my_model():
def __init__(self, n_lags=2, hid_dim_1=5, epochs=2, batch_size=1):
self.n_lags = n_lags
self.hid_dim_1 = hid_dim_1
self.epochs = epochs
self.batch_size = batch_size
self.train_generator, self.s_per_e, self.valid_generator, self.v_per_e, self.n_vars = self.read_data()
self.__model = self.model()
def read_data(self):
n_vars = 2
num_sample_minibatches = 6
num_valid_minibatches = 4
sample_IDs = range(1, self.batch_size+num_sample_minibatches)
valid_IDs = range(num_sample_minibatches+1, max(sample_IDs)+num_valid_minibatches+1)
params = {'batch_size': self.batch_size, 'n_lags': self.n_lags, 'n_vars': n_vars}
train_generator = DataGenerator(sample_IDs, **params)
valid_generator = DataGenerator(valid_IDs, **params)
s_per_e = int(len(sample_IDs) - self.batch_size + 1) #e.g. if you have 1,2,3,4,5,6 then you can create 4 sequences of length 3 (batch_size)
v_per_e = int(len(valid_IDs) - self.batch_size + 1)
return train_generator, s_per_e, valid_generator, v_per_e, n_vars
def model(self):
#https://github.com/twairball/keras_lstm_vae/blob/master/lstm_vae/vae.py
a_input = Input(shape=(self.n_lags, self.n_vars,), name='a_input')
cond_on_this = Input(shape=(self.n_vars,), name="cond_on_this")
b_lstm = LSTM(self.hid_dim_1)(a_input)
outputs = Dense(self.hid_dim_1, activation='sigmoid')(b_lstm)
my_model1 = Model([a_input, cond_on_this], outputs)
my_model1.compile(optimizer=Adam(lr=0.001), loss=binary_crossentropy)
return my_model1
def my_model_fit_generator(self):
earlystop = EarlyStopping(monitor='val_acc', patience=5, verbose=2, mode='auto')
self.__model.fit_generator(generator=self.train_generator,
validation_data=self.valid_generator,
steps_per_epoch=self.s_per_e,
epochs=self.epochs,
validation_steps = self.v_per_e,
shuffle=False,
verbose=2,
callbacks=[earlystop])
def my_model_evaluate(self):
self.my_model_fit_generator()
evaluation = self.__model.evaluate_generator(self.valid_generator, self.v_per_e, verbose=0)
return evaluation
class DataGenerator(keras.utils.Sequence):
'Generates data for Keras'
def __init__(self, list_IDs, batch_size, n_lags, n_vars, shuffle=False):
'Initialization'
self.list_IDs = list_IDs
self.batch_size = batch_size
self.n_lags = n_lags
self.n_vars = n_vars
self.shuffle = shuffle
self.on_epoch_end()
def __len__(self):
'Denotes the number of batches per epoch'
batches_per_epoch = int(np.floor(len(self.list_IDs) - self.batch_size + 1))
return batches_per_epoch
def __getitem__(self, index):
'Generate one batch of data'
#Here's my evidence that the validation minibatches are being used during training!
print('batch number: ', index+1, 'of: ', int(np.floor(len(self.list_IDs) - self.batch_size + 1)))
indexes = self.indexes[index:(index+self.batch_size)]
# Find list of IDs
list_IDs_temp = [self.list_IDs[k] for k in indexes]
# Generate data
data, cond_on_this = self.__data_generation(list_IDs_temp)
return [np.asarray(data), np.asarray(cond_on_this)], np.asarray(cond_on_this)
def on_epoch_end(self):
'Updates indexes after each epoch'
self.indexes = np.arange(len(self.list_IDs))
if self.shuffle == True:
np.random.shuffle(self.indexes)
#From MachineLearningMastery
def series_to_supervised(self, data, n_out=1, dropnan=True):
n_vars = 1 if type(data) is list else data.shape[1]
df = DataFrame(data)
cols, names = list(), list()
#input sequence t-n, ..., t-1
for i in range(self.n_lags, 0, -1): #for i in 3 to 0 not including 0
cols.append(df.shift(i))
names += [('var%d(t-%d)' % (j+1, i)) for j in range (self.n_vars)]
#forecast sequence t, t+1, ..., t+n
for i in range(0, n_out):
cols.append(df.shift(-i))
if i==0:
names += [('var%d(t)' % (j+1)) for j in range(self.n_vars)]
else:
names += [('var%d(t+%d)' % (j+1, i)) for j in range(self.n_vars)]
agg = concat(cols, axis=1)
agg.columns = names
if dropnan:
agg.dropna(inplace=True)
return agg
def __data_generation(self, list_IDs_temp):
'Generates data containing batch_size samples'
data_np_array = np.empty((self.batch_size, self.n_vars), dtype=float)
for i, ID in enumerate(list_IDs_temp):
#Read in a data file corresponding to this ID; put it into the numpy array.
data_file = './pollution_' + str(i) + '.csv'
df_data = pd.read_csv(data_file, sep=",", header=0)
df_data.columns = ['date','pollution','dew','temp','press','wnd_dir','wnd_spd','snow','rain']
df_data_vals = df_data[['pollution', 'temp']] #this is shape (24, 2)
data_np_array[i,] = np.asarray(df_data_vals)
data_s2s = np.asarray(self.series_to_supervised(data_np_array))
data_data = data_s2s[:, :int(self.n_vars*self.n_lags)]
data_cond = data_s2s[:, int(self.n_vars*self.n_lags):]
data_data = data_data.reshape((data_data.shape[0], self.n_lags, self.n_vars))
return data_data, data_cond
def run_my_model(n_lags=2, hid_dim_1=5, epochs=2, batch_size=1):
_my_model = my_model(n_lags=n_lags, hid_dim_1=hid_dim_1, epochs=epochs, batch_size=batch_size)
mymodel_evaluation = _my_model.my_model_evaluate()
return mymodel_evaluation
#Bounds for hyperparameters
bounds = [{'name': 'hid_dim_1', 'type': 'discrete', 'domain': (5, 10)}]
#Bayesian Optimization
def f(x):
evaluation = run_my_model(hid_dim_1 = int(x[:,0]), epochs = 2, batch_size = 1)
print("binary crossentropy:\t{0}".format(evaluation[0]))
print(evaluation)
return evaluation
#Optimizer instance
opt_mymodel = GPyOpt.methods.BayesianOptimization(f=f, domain=bounds, initial_design_numdata=1)
#Run optimizer
opt_mymodel.run_optimization(max_iter=2)
opt_mymodel.x_opt
相关输出：
Using TensorFlow backend.
Epoch 1/2
batch number: 1 of: 4
batch number: 1 of: 6
batch number: 2 of: 4
batch number: 2 of: 6
batch number: 3 of: 4
batch number: 3 of: 6
batch number: 4batch number: 4 of: 4
of: 6
batch number: 5 of: 6
batch number: 6 of: 6
Traceback (most recent call last):
...Error after this...