LSTM Example

原文链接

​ Figure 1. LSTM cell with three inputs and 1 output.

A way to convert symbol to number is to assign a unique integer to each symbol based on frequency of occurrence

def build_dataset(words):
    count = collections.Counter(words).most_common()
    dictionary = dict()
    for word, _ in count:
        dictionary[word] = len(dictionary)
    reverse_dictionary = dict(zip(dictionary.values(), dictionary.keys()))
    return dictionary, reverse_dictionary

上面就是采用通过词频的方式，来进行转化编码

def RNN(x, weights, biases):

    # reshape to [1, n_input]
    x = tf.reshape(x, [-1, n_input])

    # Generate a n_input-element sequence of inputs
    # (eg. [had] [a] [general] -> [20] [6] [33])
    x = tf.split(x,n_input,1)

    # 1-layer LSTM with n_hidden units.
    rnn_cell = rnn.BasicLSTMCell(n_hidden)

    # generate prediction
    outputs, states = rnn.static_rnn(rnn_cell, x, dtype=tf.float32)

    # there are n_input outputs but
    # we only want the last output
    return tf.matmul(outputs[-1], weights['out']) + biases['out']

Final notes:

1. Using int to encode symbols is easy but the “meaning” of the word is lost. Symbol to int is used to simplify the discussion on building a LSTM application using Tensorflow. Word2Vec is a more optimal way of encoding symbols to vector.
2. One-hot vector representation of output is inefficient especially if we have a realistic vocabulary size. Oxford dictionary has over 170,000 words. The example above has 112. Again, this is only for simplifying the discussion.
3. The number of inputs in this example is 3, see what happens when you use other numbers (eg 4, 5 or more).

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想法：

• one hot的进化？词语太多的话，数组170000？左右
• 关于word的meaning部分，采用word2vec的方式，
• 关于input的参数的使用？如何使用？