As your data makes its way through a pipeline, it may need to be converted into a structure compatible with your algorithm's input layer. There are many possible transformations that can be performed on the data in the pipeline. For example, in order to protect sensitive user data before it reaches a token-based classifier, you might apply a cryptographic hashing function to the tokens so that they are no longer human readable.
More typically, the types of transformations will be related to sanitization, normalization, or transposition. A sanitization operation might involve removing unnecessary whitespace or HTML tags, removing email addresses from a token stream, and removing unnecessary fields from the ...