A pipeline

In programming, a pipeline is a set of procedures connected in series, one after the other, where the output of one process is the input to the next:

You can replace any procedure in the process with a different one, perhaps better in some way, without compromising the whole system. For the model in the middle step, you can use an SVC or logistic regression:

One can also keep track of the classifier itself and build a flow diagram from the classifier. Here is a pipeline keeping track of the SVC classifier:

In the upcoming chapters, we will see how scikit-learn uses the intuitive notion of a pipeline. So far, we have used a simple one: train, predict, test.