# Lab 12 Character Sequence RNN
import tensorflow as tf
import numpy as np
tf.set_random_seed(777) # reproducibility
sample = " if you want you"
idx2char = list(set(sample)) # index -> char
char2idx = {c: i for i, c in enumerate(idx2char)} # char -> idex
# hyper parameters
dic_size = len(char2idx) # RNN input size (one hot size)
hidden_size = len(char2idx) # RNN output size
num_classes = len(char2idx) # final output size (RNN or softmax, etc.)
batch_size = 1 # one sample data, one batch
sequence_length = len(sample) - 1 # number of lstm rollings (unit #)
sample_idx = [char2idx[c] for c in sample] # char to index
x_data = [sample_idx[:-1]] # X data sample (0 ~ n-1) hello: hell
y_data = [sample_idx[1:]] # Y label sample (1 ~ n) hello: ello
X = tf.placeholder(tf.int32, [None, sequence_length]) # X data
Y = tf.placeholder(tf.int32, [None, sequence_length]) # Y label
x_one_hot = tf.one_hot(X, num_classes) # one hot: 1 -> 0 1 0 0 0 0 0 0 0 0
cell = tf.contrib.rnn.BasicLSTMCell(
num_units=hidden_size, state_is_tuple=True)
initial_state = cell.zero_state(batch_size, tf.float32)
outputs, _states = tf.nn.dynamic_rnn(
cell, x_one_hot, initial_state=initial_state, dtype=tf.float32)
# FC layer
X_for_fc = tf.reshape(outputs, [-1, hidden_size])
outputs = tf.contrib.layers.fully_connected(outputs, num_classes, activation_fn=None)
# reshape out for sequence_loss
outputs = tf.reshape(outputs, [batch_size, sequence_length, num_classes])
weights = tf.ones([batch_size, sequence_length])
sequence_loss = tf.contrib.seq2seq.sequence_loss(
logits=outputs, targets=Y, weights=weights)
loss = tf.reduce_mean(sequence_loss)
train = tf.train.AdamOptimizer(learning_rate=0.1).minimize(loss)
prediction = tf.argmax(outputs, axis=2)
with tf.Session() as sess:
sess.run(tf.global_variables_initializer())
for i in range(50):
l, _ = sess.run([loss, train], feed_dict={X: x_data, Y: y_data})
result = sess.run(prediction, feed_dict={X: x_data})
# print char using dic
result_str = [idx2char[c] for c in np.squeeze(result)]
print(i, "loss:", l, "Prediction:", ''.join(result_str))
