我正在尝试使用自适应学习率和基于Adam的梯度优化来实现一个卷积神经网络。我有以下代码:
# 学习率时间表schedule = np.array([0.0005, 0.0005, 0.0002, 0.0002, 0.0002, 0.0001, 0.0001, 0.0001, 0.00005, 0.00005, 0.00005, 0.00005, 0.00001, 0.00001, 0.00001, 0.00001, 0.00001, 0.00001, 0.00001, 0.00001])# 定义变量学习率的占位符learning_rates = tf.placeholder(tf.float32, (None),name='learning_rate')# 训练操作cross_entropy = tf.nn.softmax_cross_entropy_with_logits(logits=logits, labels=one_hot_y)loss_operation = tf.reduce_mean(cross_entropy)optimizer = tf.train.AdamOptimizer(learning_rate=learning_rates)training_operation = optimizer.minimize(loss_operation)
运行会话的代码:
..._, loss = sess.run([training_operation, loss_operation], feed_dict={x: batch_x, y: batch_y, learning_rate: schedule[i]})...
i 代表从0开始的epoch计数,所以它应该使用schedule中的第一个值。
每当我尝试运行这段代码时,我会得到以下错误:
InvalidArgumentError: 你必须为占位符张量 ‘learning_rate_2’ 提供一个值,其数据类型为 float [[Node: learning_rate_2 = Placeholderdtype=DT_FLOAT, shape=[], _device=”/job:localhost/replica:0/task:0/cpu:0″]]
有没有人遇到过相同的问题?我尝试重新初始化会话,重命名变量,但都没有用。
回答:
找到了一个中间解决方案。
...for i in range(EPOCHS): XX_train, yy_train = shuffle(X_train, y_train) # 自适应学习率的代码 optimizer = tf.train.AdamOptimizer(learning_rate = schedule[i]) for offset in range(0, num_examples, BATCH_SIZE): end = offset + BATCH_SIZE batch_x, batch_y = XX_train[offset:end], yy_train[offset:end] _, loss = sess.run([training_operation, loss_operation], feed_dict={x: batch_x, y: batch_y})...
虽然不是很优雅,但至少它能工作。