Tensorflow 神经网络能处理冗余输入吗?
我有一个完全连接的神经网络,每层有以下数量的神经元Tensorflow 神经网络能处理冗余输入吗?,tensorflow,optimization,neural-network,training-data,loss-function,Tensorflow,Optimization,Neural Network,Training Data,Loss Function,我有一个完全连接的神经网络,每层有以下数量的神经元[4,20,20,20,…,1]。我使用的是TensorFlow,4个实值输入对应于空间和时间中的特定点,即(x,y,z,t),1个实值输出对应于该点的温度。损失函数就是(x,y,z,t)中预测温度和实际温度之间的均方误差。我有一组训练数据点,其输入结构如下: (x,y,z,t): (0.11,0.12,1.00,0.41) (0.34,0.43,1.00,0.92) (0.01,0.25,1.00,0.65) (0.71,0.32,1.00
[4,20,20,20,…,1]
。我使用的是TensorFlow,4个实值输入对应于空间和时间中的特定点,即(x,y,z,t),1个实值输出对应于该点的温度。损失函数就是(x,y,z,t)中预测温度和实际温度之间的均方误差。我有一组训练数据点,其输入结构如下:
(x,y,z,t): (0.11,0.12,1.00,0.41) (0.34,0.43,1.00,0.92) (0.01,0.25,1.00,0.65) (0.71,0.32,1.00,0.49) (0.31,0.22,1.00,0.01) (0.21,0.13,1.00,0.71)
也就是说,您会注意到,训练数据在
z
中都具有相同的冗余值,但是x
、y
和t
通常不冗余。然而,我发现由于冗余,我的神经网络无法对这些数据进行训练。特别是,每次我开始训练神经网络时,它似乎失败了,损失函数变成nan
。但是,如果我改变神经网络的结构,使每一层中的神经元数量是[3,20,20,20,…,1]
,也就是说,现在数据点只对应于(x,y,t)的输入,一切工作都很好,训练也很好。但是有没有办法克服这个问题呢?(注意:无论任何变量是否相同,例如x
、y
或t
都可能是冗余的,并导致此错误。)我也尝试了不同的激活功能(例如ReLU)和改变网络中的层数和神经元数,但这些更改并不能解决问题
我的问题是:有没有办法在保持冗余的z
作为输入的同时仍然训练神经网络?碰巧我目前考虑的特定训练数据集都是冗余的,但一般来说,我将来会有来自不同的z
的数据。因此,寻求一种确保神经网络在当前时刻能够稳健地处理输入的方法
下面是一个简单的工作示例。运行此示例时,损失输出为nan
,但如果您只是取消注释第12行中的x_z
,以确保x_z
中现在有变化,则不再存在任何问题。但这不是一个解决方案,因为目标是使用所有常量值的原始x_z
import numpy as np
import tensorflow as tf
end_it = 10000 #number of iterations
frac_train = 1.0 #randomly sampled fraction of data to create training set
frac_sample_train = 0.1 #randomly sampled fraction of data from training set to train in batches
layers = [4, 20, 20, 20, 20, 20, 20, 20, 20, 1]
len_data = 10000
x_x = np.array([np.linspace(0.,1.,len_data)])
x_y = np.array([np.linspace(0.,1.,len_data)])
x_z = np.array([np.ones(len_data)*1.0])
#x_z = np.array([np.linspace(0.,1.,len_data)])
x_t = np.array([np.linspace(0.,1.,len_data)])
y_true = np.array([np.linspace(-1.,1.,len_data)])
N_train = int(frac_train*len_data)
idx = np.random.choice(len_data, N_train, replace=False)
x_train = x_x.T[idx,:]
y_train = x_y.T[idx,:]
z_train = x_z.T[idx,:]
t_train = x_t.T[idx,:]
v1_train = y_true.T[idx,:]
sample_batch_size = int(frac_sample_train*N_train)
np.random.seed(1234)
tf.set_random_seed(1234)
import logging
logging.getLogger('tensorflow').setLevel(logging.ERROR)
tf.logging.set_verbosity(tf.logging.ERROR)
class NeuralNet:
def __init__(self, x, y, z, t, v1, layers):
X = np.concatenate([x, y, z, t], 1)
self.lb = X.min(0)
self.ub = X.max(0)
self.X = X
self.x = X[:,0:1]
self.y = X[:,1:2]
self.z = X[:,2:3]
self.t = X[:,3:4]
self.v1 = v1
self.layers = layers
self.weights, self.biases = self.initialize_NN(layers)
self.sess = tf.Session(config=tf.ConfigProto(allow_soft_placement=False,
log_device_placement=False))
self.x_tf = tf.placeholder(tf.float32, shape=[None, self.x.shape[1]])
self.y_tf = tf.placeholder(tf.float32, shape=[None, self.y.shape[1]])
self.z_tf = tf.placeholder(tf.float32, shape=[None, self.z.shape[1]])
self.t_tf = tf.placeholder(tf.float32, shape=[None, self.t.shape[1]])
self.v1_tf = tf.placeholder(tf.float32, shape=[None, self.v1.shape[1]])
self.v1_pred = self.net(self.x_tf, self.y_tf, self.z_tf, self.t_tf)
self.loss = tf.reduce_mean(tf.square(self.v1_tf - self.v1_pred))
self.optimizer = tf.contrib.opt.ScipyOptimizerInterface(self.loss,
method = 'L-BFGS-B',
options = {'maxiter': 50,
'maxfun': 50000,
'maxcor': 50,
'maxls': 50,
'ftol' : 1.0 * np.finfo(float).eps})
init = tf.global_variables_initializer()
self.sess.run(init)
def initialize_NN(self, layers):
weights = []
biases = []
num_layers = len(layers)
for l in range(0,num_layers-1):
W = self.xavier_init(size=[layers[l], layers[l+1]])
b = tf.Variable(tf.zeros([1,layers[l+1]], dtype=tf.float32), dtype=tf.float32)
weights.append(W)
biases.append(b)
return weights, biases
def xavier_init(self, size):
in_dim = size[0]
out_dim = size[1]
xavier_stddev = np.sqrt(2/(in_dim + out_dim))
return tf.Variable(tf.truncated_normal([in_dim, out_dim], stddev=xavier_stddev), dtype=tf.float32)
def neural_net(self, X, weights, biases):
num_layers = len(weights) + 1
H = 2.0*(X - self.lb)/(self.ub - self.lb) - 1.0
for l in range(0,num_layers-2):
W = weights[l]
b = biases[l]
H = tf.tanh(tf.add(tf.matmul(H, W), b))
W = weights[-1]
b = biases[-1]
Y = tf.add(tf.matmul(H, W), b)
return Y
def net(self, x, y, z, t):
v1_out = self.neural_net(tf.concat([x,y,z,t], 1), self.weights, self.biases)
v1 = v1_out[:,0:1]
return v1
def callback(self, loss):
global Nfeval
print(str(Nfeval)+' - Loss in loop: %.3e' % (loss))
Nfeval += 1
def fetch_minibatch(self, x_in, y_in, z_in, t_in, den_in, N_train_sample):
idx_batch = np.random.choice(len(x_in), N_train_sample, replace=False)
x_batch = x_in[idx_batch,:]
y_batch = y_in[idx_batch,:]
z_batch = z_in[idx_batch,:]
t_batch = t_in[idx_batch,:]
v1_batch = den_in[idx_batch,:]
return x_batch, y_batch, z_batch, t_batch, v1_batch
def train(self, end_it):
it = 0
while it < end_it:
x_res_batch, y_res_batch, z_res_batch, t_res_batch, v1_res_batch = self.fetch_minibatch(self.x, self.y, self.z, self.t, self.v1, sample_batch_size) # Fetch residual mini-batch
tf_dict = {self.x_tf: x_res_batch, self.y_tf: y_res_batch, self.z_tf: z_res_batch, self.t_tf: t_res_batch,
self.v1_tf: v1_res_batch}
self.optimizer.minimize(self.sess,
feed_dict = tf_dict,
fetches = [self.loss],
loss_callback = self.callback)
def predict(self, x_star, y_star, z_star, t_star):
tf_dict = {self.x_tf: x_star, self.y_tf: y_star, self.z_tf: z_star, self.t_tf: t_star}
v1_star = self.sess.run(self.v1_pred, tf_dict)
return v1_star
model = NeuralNet(x_train, y_train, z_train, t_train, v1_train, layers)
Nfeval = 1
model.train(end_it)
将numpy导入为np
导入tensorflow作为tf
end_it=10000#迭代次数
frac_train=1.0#随机抽样的部分数据以创建训练集
frac_sample_train=0.1#从训练集中随机抽样的数据部分,以批量方式进行训练
层=[4,20,20,20,20,20,20,20,20,20,1]
len_数据=10000
x_x=np.array([np.linspace(0,1,len_数据)])
x_y=np.array([np.linspace(0,1,len_数据)])
x_z=np.数组([np.个(len_数据)*1.0])
#x_z=np.数组([np.linspace(0,1,len_数据)])
x_t=np.array([np.linspace(0,1,len_数据)])
y_true=np.array([np.linspace(-1,1,len_数据)])
N_列=整数(分形列*长度数据)
idx=np.random.choice(len_数据,N_序列,replace=False)
x_train=x_x.T[idx,:]
y_train=x_y.T[idx,:]
z_train=x_z.T[idx,:]
t_train=x_t.t[idx,:]
v1\u train=y\u true.T[idx,:]
样品批次尺寸=int(压裂样品系列*N系列)
np.random.seed(1234)
tf.设置随机种子(1234)
导入日志记录
logging.getLogger('tensorflow').setLevel(logging.ERROR)
设置详细性(tf.logging.ERROR)
类神经网络:
定义初始层(self、x、y、z、t、v1、层):
X=np.连接([X,y,z,t],1)
self.lb=X.min(0)
self.ub=X.max(0)
self.X=X
self.x=x[:,0:1]
self.y=X[:,1:2]
self.z=X[:,2:3]
self.t=X[:,3:4]
self.v1=v1
self.layers=层
self.weights,self.bias=self.initialize_NN(层)
self.sess=tf.Session(config=tf.ConfigProto(allow\u soft\u placement=False,
日志(设备位置=假))
self.x_tf=tf.placeholder(tf.float32,shape=[None,self.x.shape[1]]
self.y_tf=tf.placeholder(tf.float32,shape=[None,self.y.shape[1]]
self.z_tf=tf.placeholder(tf.float32,shape=[None,self.z.shape[1]]
self.t_tf=tf.placeholder(tf.float32,shape=[None,self.t.shape[1]]
self.v1_tf=tf.placeholder(tf.float32,shape=[None,self.v1.shape[1]]
self.v1_pred=self.net(self.x_tf、self.y_tf、self.z_tf、self.t_tf)
self.loss=tf.reduce_mean(tf.square(self.v1_tf-self.v1_pred))
self.optimizer=tf.contrib.opt.ScipyOptimizerInterface(self.loss,
方法='L-BFGS-B',
选项={'maxiter':50,
“maxfun”:50000,
“maxcor”:50岁,
“最大值”:50,
“ftol”:1.0*np.finfo(float.eps})
init=tf.global_variables_initializer()
self.sess.run(init)
def初始化\u NN(自身,层):
权重=[]
偏差=[]
num_layers=len(层)
对于范围内的l(0,num_层-1):
W=self.xavier_init(大小=[layers[l],layers[l+1]]
b=tf.Variable(tf.zero([1,layers[l+1]],dtype=tf.float32),dtype=tf.float32)
权重。附加(W)
偏见。附加(b)
返回权重、偏差
def xavier_初始值(自身,大小):
in_dim=大小[0]
out_dim=尺寸[1]