我的模型的损失值为0,但它只是将所有输入分类到同一个类中,出了什么问题?
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我训练了这个模型来对数据集中的图像进行分类。当未训练权重时,损失值似乎正常,但在第一个时期之后,损失减少到0,并且所有输入图像被分类为0级。
如果添加了正则化,则权重更新更慢,但最终得到相同的结果,比如分类为0级且损失值为0的所有图像。
import tensorflow as tf
from tensorflow import keras
import numpy as np
EPOCH = 10
BATCH_SIZE = 30
DATA_SIZE = 60000
REGULARIZER = 0.001
def main():
fashion_mnist = keras.datasets.fashion_mnist
(train_images, train_labels), (test_images, test_labels) = fashion_mnist.load_data()
train_images = train_images / 255.0
test_images = test_images / 255.0
train_labels = train_labels.reshape((60000, 1))
train_images = train_images.reshape((60000, 784))
test_images = test_images.reshape((10000, 784))
judge_labels = test_labels.reshape((10000, 1))
x = tf.placeholder(tf.float32, (None, 784))
y_ = tf.placeholder(tf.float32, (None, 1))
w1 = tf.Variable(np.random.rand(784 * 24).reshape([784, 24]) * 10, dtype=tf.float32)
# tf.add_to_collection('losses', tf.contrib.layers.l2_regularizer(REGULARIZER)(w1))
w2 = tf.Variable(np.random.rand(24 * 24).reshape([24, 24]) * 10, dtype=tf.float32)
# tf.add_to_collection('losses', tf.contrib.layers.l2_regularizer(REGULARIZER)(w2))
w3 = tf.Variable(np.random.rand(24 * 10).reshape([24, 10]) * 10, dtype=tf.float32)
# tf.add_to_collection('losses', tf.contrib.layers.l2_regularizer(REGULARIZER)(w3))
bias1 = tf.constant(1, shape=(24,), dtype=tf.float32)
bias2 = tf.constant(1, shape=(24,), dtype=tf.float32)
y1 = tf.nn.relu(tf.matmul(x, w1) + bias1)
y2 = tf.nn.relu(tf.matmul(y1, w2) + bias2)
y = tf.matmul(y2, w3)
predict = tf.argmax(y, axis=1)
y_spy = tf.nn.softmax(y, axis=1)
ce = tf.nn.sparse_softmax_cross_entropy_with_logits(labels=tf.argmax(y_, 1), logits=y)
# loss = tf.reduce_mean(ce) + tf.add_n(tf.get_collection('losses'))
loss = tf.reduce_mean(ce)
train_step = tf.train.GradientDescentOptimizer(0.001).minimize(loss)
with tf.Session() as sess:
init_op = tf.global_variables_initializer()
sess.run(init_op)
print('current out loss: ', end='')
print(sess.run(loss, feed_dict={x: test_images, y_: judge_labels}))
pre = sess.run(predict, feed_dict={x: test_images})
miss = pre - test_labels
print('right number: ', end='')
print((np.sum(miss == 0)))
for epoch in range(EPOCH):
for i in range(DATA_SIZE // BATCH_SIZE):
start = i * BATCH_SIZE
end = (i + 1) * BATCH_SIZE
_ = sess.run([train_step], feed_dict={x: train_images[start:end],
y_: train_labels[start:end]})
print('epochs %d :' % epoch)
print('current in loss: ', end='')
print(sess.run(loss, feed_dict={x: train_images[start:end],
y_: train_labels[start:end]}))
print('current out loss: ', end='')
print(sess.run(loss, feed_dict={x: test_images, y_: judge_labels}))
miss = sess.run(predict, feed_dict={x: test_images}) - test_labels
print('right number: ', end='')
print((np.sum(miss == 0)))
if __name__ == "__main__":
main()
答案
错误1:应该是损失函数
ce = tf.nn.sparse_softmax_cross_entropy_with_logits(labels=tf.reshape(y_, [-1]), logits=y)
因为标签是此损失函数的平坦值。 (将y占位符更改为int32类型)
错误2:重量初始化为非常大的值。
GradientDescentOptimizer
是非常缓慢的优化器。请改用AdamOptimizer
固定代码:
import tensorflow as tf
from tensorflow import keras
import numpy as np
EPOCH = 10
BATCH_SIZE = 64
DATA_SIZE = 60000
REGULARIZER = 0.001
def main():
fashion_mnist = keras.datasets.fashion_mnist
(train_images, train_labels), (test_images, test_labels) = fashion_mnist.load_data()
train_images = train_images / 255.0
test_images = test_images / 255.0
train_labels = train_labels.reshape((60000, 1))
train_images = train_images.reshape((60000, 784))
test_images = test_images.reshape((10000, 784))
judge_labels = test_labels.reshape((10000, 1))
x = tf.placeholder(tf.float32, (None, 784))
y_ = tf.placeholder(tf.int32, (None, 1))
w1 = tf.Variable(np.random.rand(784 * 24).reshape([784, 24]), dtype=tf.float32)
# tf.add_to_collection('losses', tf.contrib.layers.l2_regularizer(REGULARIZER)(w1))
w2 = tf.Variable(np.random.rand(24 * 24).reshape([24, 24]), dtype=tf.float32)
# tf.add_to_collection('losses', tf.contrib.layers.l2_regularizer(REGULARIZER)(w2))
w3 = tf.Variable(np.random.rand(24 * 10).reshape([24, 10]), dtype=tf.float32)
# tf.add_to_collection('losses', tf.contrib.layers.l2_regularizer(REGULARIZER)(w3))
bias1 = tf.constant(1, shape=(24,), dtype=tf.float32)
bias2 = tf.constant(1, shape=(24,), dtype=tf.float32)
y1 = tf.nn.relu(tf.matmul(x, w1) + bias1)
y2 = tf.nn.relu(tf.matmul(y1, w2) + bias2)
y = tf.matmul(y2, w3)
predict = tf.argmax(y, axis=1)
y_spy = tf.nn.softmax(y, axis=1)
ce = tf.nn.sparse_softmax_cross_entropy_with_logits(labels=tf.reshape(y_, [-1]), logits=y)
# loss = tf.reduce_mean(ce) + tf.add_n(tf.get_collection('losses'))
loss = tf.reduce_mean(ce)
train_step = tf.train.AdamOptimizer(0.001).minimize(loss)
with tf.Session() as sess:
init_op = tf.global_variables_initializer()
sess.run(init_op)
print('current out loss: ', end='')
print(sess.run(loss, feed_dict={x: test_images, y_: judge_labels}))
pre = sess.run(predict, feed_dict={x: test_images})
miss = pre - test_labels
print('right number: ', end='')
print((np.sum(miss == 0)))
for epoch in range(EPOCH):
for i in range(DATA_SIZE // BATCH_SIZE):
start = i * BATCH_SIZE
end = (i + 1) * BATCH_SIZE
_ = sess.run([train_step], feed_dict={x: train_images[start:end],
y_: train_labels[start:end]})
print('epochs %d :' % epoch)
print('current in loss: ', end='')
print(sess.run(loss, feed_dict={x: train_images[start:end],
y_: train_labels[start:end]}))
print('current out loss: ', end='')
print(sess.run(loss, feed_dict={x: test_images, y_: judge_labels}))
miss = sess.run(predict, feed_dict={x: test_images}) - test_labels
print('right number: ', end='')
print((np.sum(miss == 0)))
miss = sess.run(predict, feed_dict={x: test_images})
print (miss[0:10], test_labels[0:10])
if __name__ == "__main__":
main()
输出(选择性):
...
Sample predictions: [9 2 4 3 2 4 4 4 7 7], Actual: [9 2 1 1 6 1 4 6 5 7]
...
Sample predictions: [9 2 1 1 6 1 4 6 1 7], Actual: [9 2 1 1 6 1 4 6 5 7]
...
Sample predictions: [7 2 1 1 6 1 4 6 1 7], Actual: [9 2 1 1 6 1 4 6 5 7]
...
Sample predictions: [9 2 1 1 6 1 4 6 1 7], Actual: [9 2 1 1 6 1 4 6 5 7]
...
每个纪元的代码,包括列车,验证损失和列车,验证准确性和改组列车数据
import tensorflow as tf
from tensorflow import keras
import numpy as np
from sklearn.metrics import classification_report, accuracy_score
EPOCH = 30
BATCH_SIZE = 64
DATA_SIZE = 60000
REGULARIZER = 0.001
def main():
fashion_mnist = keras.datasets.fashion_mnist
(train_images, train_labels), (test_images, test_labels) = fashion_mnist.load_data()
train_images = train_images / 255.0
test_images = test_images / 255.0
train_labels = train_labels.reshape((60000, 1))
train_images = train_images.reshape((60000, 784))
test_images = test_images.reshape((10000, 784))
judge_labels = test_labels.reshape((10000, 1))
x = tf.placeholder(tf.float32, (None, 784))
y_ = tf.placeholder(tf.int32, (None, 1))
w1 = tf.Variable(np.random.rand(784 * 24).reshape([784, 24]), dtype=tf.float32)
tf.add_to_collection('losses', tf.contrib.layers.l2_regularizer(REGULARIZER)(w1))
w2 = tf.Variable(np.random.rand(24 * 24).reshape([24, 24]), dtype=tf.float32)
tf.add_to_collection('losses', tf.contrib.layers.l2_regularizer(REGULARIZER)(w2))
w3 = tf.Variable(np.random.rand(24 * 10).reshape([24, 10]), dtype=tf.float32)
tf.add_to_collection('losses', tf.contrib.layers.l2_regularizer(REGULARIZER)(w3))
bias1 = tf.constant(1, shape=(24,), dtype=tf.float32)
bias2 = tf.constant(1, shape=(24,), dtype=tf.float32)
y1 = tf.nn.relu(tf.matmul(x, w1) + bias1)
y2 = tf.nn.relu(tf.matmul(y1, w2) + bias2)
y = tf.matmul(y2, w3)
predict = tf.argmax(y, axis=1)
ce = tf.nn.sparse_softmax_cross_entropy_with_logits(labels=tf.reshape(y_, [-1]), logits=y)
loss = tf.reduce_mean(ce)
train_step = tf.train.AdamOptimizer(0.001).minimize(loss)
with tf.Session() as sess:
init_op = tf.global_variables_initializer()
sess.run(init_op)
idx = np.arange(DATA_SIZE)
for epoch in range(EPOCH):
train_loss = list()
train_predict = list()
np.random.shuffle(idx)
train_images = train_images[idx]
train_labels = train_labels[idx]
for i in range(DATA_SIZE // BATCH_SIZE):
start = i * BATCH_SIZE
end = (i + 1) * BATCH_SIZE
_, loss_, p_ = sess.run([train_step, loss, predict], feed_dict={x: train_images[start:end],
y_: train_labels[start:end]})
train_loss.append(loss_)
train_predict.extend(p_)
test_loss, test_predict = sess.run([loss, predict], feed_dict={x: test_images,
y_: judge_labels})
print ("Epoch: {}, Train Loss: {:.3f}, Test Loss: {:.3f},"\
"Train Acc: {:.3f}, Test Acc: {:.3f}".format(
epoch+1, np.mean(train_loss), test_loss,
accuracy_score(train_labels[0:len(train_predict)], train_predict),
accuracy_score(judge_labels, test_predict)))
if __name__ == "__main__":
main()
输出:
....
Epoch: 27, Train Loss: 0.842, Test Loss: 1.015,Train Acc: 0.816, Test Acc: 0.798
Epoch: 28, Train Loss: 0.832, Test Loss: 0.880,Train Acc: 0.816, Test Acc: 0.806
Epoch: 29, Train Loss: 0.788, Test Loss: 0.886,Train Acc: 0.820, Test Acc: 0.805
Epoch: 30, Train Loss: 0.704, Test Loss: 0.742,Train Acc: 0.826, Test Acc: 0.815
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