import tensorflow as tf
from tensorflow.examples.tutorials.mnist import input_data

# 載入資料
mnist = input_data.read_data_sets('MNIST_data', one_hot=True)

# 輸入圖片是28*28
n_inputs = 28  # 輸入一行，一行有28個數據
max_time = 28  # 一共有28行
lstm_size = 100  # 隱藏單元
n_classes = 10  # 10個分類
batch_size = 50  # 每批次有50個樣本
n_batch = mnist.train.num_examples // batch_size

# 這裡的None表示第一個唯獨可以是任意長度
 

x = tf.placeholder(tf.float32, [None, 784])
# 正確的標籤
y = tf.placeholder(tf.float32, [None, 10])

# 初始化權值
weights = tf.Variable(tf.truncated_normal([lstm_size, n_classes], stddev=0.1))
# 初始化偏置值
biases = tf.Variable(tf.constant(0.1, shape=[n_classes]))


# 定義RNN網路
def RNN(X, weights, biases):
    # inputs = [batch_size, max_time, n_inout]
 

    inputs = tf.reshape(X, [-1, max_time, n_inputs])
    # 定義LSTM基本CELL
    lstm_cell = tf.contrib.rnn.core_rnn_cell.BasicLSTMCell(lstm_size)
    # final_state[0] 是cell state
    # final_state[1] 是hidden_state
    outputs, final_state = tf.nn.dynamic_rnn(lstm_cell, inputs, dtype=tf.float32)
    results = tf.nn.softmax(tf.matmul(final_state[1
 
], weights) + biases)
    return results


# 計算RNN的返回結果
prediction = RNN(x, weights, biases)
# 損失函式
cross_entropy = tf.reduce_mean(tf.nn.softmax_cross_entropy_with_logits(labels=y, logits=prediction))
# 使用AdamOptimizer進行優化
train_step = tf.train.AdamOptimizer(1e-4).minimize(cross_entropy)
# 結果放在一個布林型列表中
crroect_prediction = tf.equal(tf.argmax(y, 1), tf.argmax(prediction, 1))
# 求準確率
accuracy = tf.reduce_mean(tf.cast(crroect_prediction, tf.float32))
# 初始化
init = tf.global_variables_initializer()

with tf.Session() as sess:
    sess.run(init)
    for epoch in range(6):
        for batch in range(n_batch):
            batch_xs, batch_ys = mnist.train.next_batch(batch_size)
            sess.run(train_step, feed_dict={x: batch_xs, y: batch_ys})

        acc = sess.run(accuracy, feed_dict={x: mnist.test.images, y: mnist.test.labels})
        print("Iter " + str(epoch) + ", Testing Accuracy= " + str(acc))

Iter 0, Testing Accuracy= 0.7428
Iter 1, Testing Accuracy= 0.7918
Iter 2, Testing Accuracy= 0.8366
Iter 3, Testing Accuracy= 0.8964
Iter 4, Testing Accuracy= 0.9123
Iter 5, Testing Accuracy= 0.9263