Sage-Tips

Is RNN suitable for sequential data?

Recurrent neural networks (RNN) are the state of the art algorithm for sequential data and are used by Apple’s Siri and and Google’s voice search. It is the first algorithm that remembers its input, due to an internal memory, which makes it perfectly suited for machine learning problems that involve sequential data.

What are sequences in RNN?

Sequence models are the machine learning models that input or output sequences of data. Sequential data includes text streams, audio clips, video clips, time-series data and etc. Recurrent Neural Networks (RNNs) is a popular algorithm used in sequence models.

What is the sequence length?

Last modified April 10, 2018. This indicates the number of amino acids in the canonical sequence displayed by default in the entry’s Sequence section.

What are the limitations and applications of RNN?

Disadvantages

• Due to its recurrent nature, the computation is slow.
• Training of RNN models can be difficult.
• If we are using relu or tanh as activation functions, it becomes very difficult to process sequences that are very long.
• Prone to problems such as exploding and gradient vanishing.

What is a drawback to building an architecture with an RNN or Lstm?

Nevertheless, there are drawbacks to RNNs. First, it fails to store information for a longer period of time. At times, a reference to certain information stored quite a long time ago is required to predict the current output. But RNNs are absolutely incapable of handling such “long-term dependencies”.

How many dimensions are required for output of an RNN layer?

Before we get down to business, an important thing to note is that the RNN input needs to have 3 dimensions. Typically it would be batch size, the number of steps and number of features.

What are RNN units?

The RNN unit in TensorFlow is called the “RNN cell”. It retains information from one time step to another flowing through the unrolled RNN units. Each unrolled RNN unit has a hidden state. The current time steps hidden state is calculated using information of the previous time step’s hidden state and the current input.

How can RNN handle time series data?

The reason that RNN can handle time series is that RNN has a recurrent hidden state whose activation at each time is dependent on that of the previous time. Long short-term memory units (LSTMs) are one type of RNN, which make each recurrent unit to adaptively capture dependencies of different time scales.

How many times does an RNN unroll in a given sequence?

Since an RNN is, by definition, recurrent, it unrolls many times when you use it. It unrolls, in the sequence dimension, as many times as items in your sequence. If you have a sequence of length one, like if you have a single word, it means that it doesn’t unroll, since there is nothing to memorize (hidden and cell state, in RNN terminology).

Do keras RNN Training examples have a fixed sequence length?

In the keras documentation, it says the input to an RNN layer must have shape (batch_size, timesteps, input_dim). This suggests that all the training examples have a fixed sequence length, namely timesteps. But this is not especially typical, is it?

Why are RNNs provided with more input samples?

In general, RNNs are provided with the input samples which contain more interdependencies. Also they have a significant representation for keeping the information about the past time steps. The output produced at time t 1 affects the parameter available at time t + 1 1.