Machine Learning for OpenCV 4 - Second Edition

Understanding logistic regression

Before we start off with this section, let me issue warning—logistic regression, despite its name, is actually a model for classification, specifically when you have two classes. It derives its name from the logistic function (or sigmoid) it uses to convert any real-valued input x into a predicted output value ŷ that takes values between 0 and 1, as shown in the following diagram:

Rounding ŷ to the nearest integer effectively classifies the input as belonging either to class 0 or 1.

Of course, most often, our problems have more than one input or feature value, x. For example, the Iris dataset provides a total ...