python-kerasHow do I use the pad_sequences function in Python Keras?

The pad_sequences function in Python Keras is used to ensure that all sequences in a list have the same length. This is important for neural networks, as inputs must be consistently sized in order to be processed.

For example, to pad a sequence of length 4 to a maximum length of 6, the code would be:

from keras.preprocessing.sequence import pad_sequences

input_sequence = [1, 2, 3, 4]
padded_sequence = pad_sequences([input_sequence], maxlen=6, padding='post')

print(padded_sequence)

The output of this code would be [[1 2 3 4 0 0]].

The code is composed of the following parts:

• from keras.preprocessing.sequence import pad_sequences: imports the pad_sequences function from the Keras library.
• input_sequence = [1, 2, 3, 4]: defines the input sequence.
• pad_sequences([input_sequence], maxlen=6, padding='post'): uses the pad_sequences function to pad the input sequence to a maximum length of 6, with padding added to the end of the sequence (post).
• print(padded_sequence): prints the padded sequence.

Helpful links

• Keras Documentation - pad_sequences
• Towards Data Science - How to use pad_sequences in Keras

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