实际上我正在使用AlexNet将我的图像分为两组，我在一批60张图像中将图像输入到模型中，每批次后我得到的损失是6到7位数大（）对于ex.1428529.0），在这里我很困惑，为什么我的损失是如此大的价值，因为在MNIST数据集上我得到的损失与此相比非常小。任何人都可以解释我为什么会得到这么大的损失价值 提前致谢; - ）
以下是代码： -
import tensorflow as tf
import matplotlib.pyplot as plt
import numpy as np
import os
img_size = 227
num_channels = 1
img_flat_size = img_size * img_size
num_classes = 2
drop = 0.5
x = tf.placeholder(tf.float32,[None,img_flat_size])
y = tf.placeholder(tf.float32,[None,num_classes])
drop_p = tf.placeholder(tf.float32)
def new_weight(shape):
return tf.Variable(tf.random_normal(shape))
def new_bias(size):
return tf.Variable(tf.random_normal(size))
def new_conv(x,num_input_channels,filter_size,num_filters,stride,padd="SAME"):
shape = [filter_size,filter_size,num_input_channels,num_filters]
weight = new_weight(shape)
bias = new_bias([num_filters])
conv = tf.nn.conv2d(x,weight,strides=[1,stride,stride,1],padding=padd)
conv = tf.nn.bias_add(conv,bias)
return tf.nn.relu(conv)
def new_max_pool(x,k,stride):
max_pool = tf.nn.max_pool(x,ksize=[1,k,k,1],strides=[1,stride,stride,1],padding="VALID")
return max_pool
def flatten_layer(layer):
layer_shape = layer.get_shape()
num_features = layer_shape[1:4].num_elements()
flat_layer = tf.reshape(layer,[-1,num_features])
return flat_layer,num_features
def new_fc_layer(x,num_input,num_output):
weight = new_weight([num_input,num_output])
bias = new_bias([num_output])
fc_layer = tf.matmul(x,weight) + bias
return fc_layer
def lrn(x, radius, alpha, beta, bias=1.0):
"""Create a local response normalization layer."""
return tf.nn.local_response_normalization(x, depth_radius=radius,
alpha=alpha, beta=beta,
bias=bias)
def AlexNet(x,drop,img_size):
x = tf.reshape(x,shape=[-1,img_size,img_size,1])
conv1 = new_conv(x,num_channels,11,96,4,"VALID")
max_pool1 = new_max_pool(conv1,3,2)
norm1 = lrn(max_pool1, 2, 2e-05, 0.75)
conv2 = new_conv(norm1,96,5,256,1)
max_pool2 = new_max_pool(conv2,3,2)
norm2 = lrn(max_pool2, 2, 2e-05, 0.75)
conv3 = new_conv(norm2,256,3,384,1)
conv4 = new_conv(conv3,384,3,384,1)
conv5 = new_conv(conv4,384,3,256,1)
max_pool3 = new_max_pool(conv5,3,2)
layer , num_features = flatten_layer(max_pool3)
fc1 = new_fc_layer(layer,num_features,4096)
fc1 = tf.nn.relu(fc1)
fc1 = tf.nn.dropout(fc1,drop)
fc2 = new_fc_layer(fc1,4096,4096)
fc2 = tf.nn.relu(fc2)
fc2 = tf.nn.dropout(fc2,drop)
out = new_fc_layer(fc2,4096,2)
return out #, tf.nn.softmax(out)
def read_and_decode(tfrecords_file, batch_size):
'''read and decode tfrecord file, generate (image, label) batches
Args:
tfrecords_file: the directory of tfrecord file
batch_size: number of images in each batch
Returns:
image: 4D tensor - [batch_size, width, height, channel]
label: 1D tensor - [batch_size]
'''
# make an input queue from the tfrecord file
filename_queue = tf.train.string_input_producer([tfrecords_file])
reader = tf.TFRecordReader()
_, serialized_example = reader.read(filename_queue)
img_features = tf.parse_single_example(
serialized_example,
features={
'label': tf.FixedLenFeature([], tf.int64),
'image_raw': tf.FixedLenFeature([], tf.string),
})
image = tf.decode_raw(img_features['image_raw'], tf.uint8)
##########################################################
# you can put data augmentation here, I didn't use it
##########################################################
# all the images of notMNIST are 28*28, you need to change the image size if you use other dataset.
image = tf.reshape(image, [227, 227])
label = tf.cast(img_features['label'], tf.int32)
image_batch, label_batch = tf.train.batch([image, label],
batch_size= batch_size,
num_threads= 1,
capacity = 6000)
return tf.reshape(image_batch,[batch_size,227*227*1]), tf.reshape(label_batch, [batch_size])
pred = AlexNet(x,drop_p,img_size) #pred
loss = tf.reduce_mean(tf.nn.softmax_cross_entropy_with_logits(logits=pred,labels=y))
optimiser = tf.train.AdamOptimizer(learning_rate = 0.001).minimize(loss)
correct_pred = tf.equal(tf.argmax(pred,1),tf.argmax(y,1))
accuracy = tf.reduce_mean(tf.cast(correct_pred,tf.float32))
cost = tf.summary.scalar('loss',loss)
init = tf.global_variables_initializer()
with tf.Session() as sess:
sess.run(init)
merge_summary = tf.summary.merge_all()
summary_writer = tf.summary.FileWriter('./AlexNet',graph = tf.get_default_graph())
tf_record_file = 'train.tfrecords'
x_val ,y_val = read_and_decode(tf_record_file,20)
y_val = tf.one_hot(y_val,depth=2,on_value=1,off_value=0)
coord = tf.train.Coordinator()
threads = tf.train.start_queue_runners(coord=coord)
x_val = x_val.eval()
y_val = y_val.eval()
epoch = 2
for i in range(epoch):
_, summary= sess.run([optimiser,merge_summary],feed_dict={x:x_val,y:y_val,drop_p:drop})
summary_writer.add_summary(summary,i)
loss_a,accu = sess.run([loss,accuracy],feed_dict={x:x_val,y:y_val,drop_p:1.0})
print "Epoch "+str(i+1) +', Minibatch Loss = '+ \
"{:.6f}".format(loss_a) + ', Training Accuracy = '+ \
'{:.5f}'.format(accu)
print "Optimization Finished!"
tf_record_file1 = 'test.tfrecords'
x_v ,y_v = read_and_decode(tf_record_file1,10)
y_v = tf.one_hot(y_v,depth=2,on_value=1,off_value=0)
coord1 = tf.train.Coordinator()
threads1 = tf.train.start_queue_runners(coord=coord1)
x_v = sess.run(x_v)
y_v = sess.run(y_v)
print "Testing Accuracy : "
print sess.run(accuracy,feed_dict={x:x_v,y:y_v,drop_p:1.0})
coord.request_stop()
coord.join(threads)
coord1.request_stop()
coord1.join(threads1)
答案 0 :(得分：0)
看看confusion matrix是什么。它是一个绩效评估员。此外，您应该比较您的精确度与召回率。精确度是阳性预测的准确性，召回率是分类器正确检测到的阳性实例的比率。通过结合精度和召回，您可以得到F_1 score，它会继续评估模型的问题。
我建议您使用Scikit-Learn和TensorFlow 选择动手机器学习文本。这是一本真正全面的书，涵盖了我上面详细描述的内容。