Chapter 2: 'Perceptron' object has no attribute 'errors_' about python-machine-learning-book-2nd-edition

[rasbt]

Hey, there,

sorry about the confusion, but the errors_ attribute does not exist prior to calling fit. There's a small paragraph about that on pg. 24:

We will take an object-oriented approach to define the perceptron interface as a Python class, which allows us to initialize new Perceptron objects that can learn from data via a fit method, and make predictions via a separate predict method. As a convention, we append an underscore (_) to attributes that are not being created upon the initialization of the object but by calling the object's other methods, for example, self.w_.

But yeah, that's easy to overlook :). Basically, that's being done to be consistent with scikit-learn, which is introduced in the next chapter.

Hope that clarifies (and addresses) the issue! :)