18. Recurrent Neural Networks#
Often data arise as sequences:
Documents are sequence of words, and their relative positions have meaning
Time-series such as weather data or financial indices.
Recorded speech or music.
Handwriting, such as doctor’s notes.
The feature for each observation is a sequence of vectors \(X={X_1,X_2,...,X_L}\)
The target Y is often a single variable such as Sentiment, or a one-hot vector for multiclass.
Y can also be a sequence, such as the same document in a different language.

The same wights \(W\), \(U\) and \(B\) are used at each step in the sequence - hence the term recurrent.
19. Example (IMDB Reviews)#

20. Time Series Forecasting#

21. Traditional autoregression forecaster#

22. When to use Deep Learning#
