# What is the point of ActiveClassification?

I must be missing something here - it seems that the first argument to ActiveClassification is your target function, but if you already know that function then why are you trying to learn it?

Examples:

f = # > 50 &;
aco = ActiveClassification[f, {2, 5, 58, 74, 17, 29, 66, 12, 90, 77}];
c = aco["ClassifierFunction"]


But c is only an approximation to f... so I'm confused.

It helps if you think of f as an oracle that is hard to get to, model, or just takes a long to time to produce an answer. So, an approximation is often what you need. For example, one job that is not easy to write a simple model for is document classification; even something as simple as "is this document relevant?" is not that simple. So, in that case, f would display a document with buttons allowing you to indicate relevance. In this way, you can train a computational model that can do the job of the classifier with reasonable efficacy. Also, ActiveClassification can further refine its model using the option InitialEvaluationHistory to start where the previous session left off. So, if you monitor the model's false-positives/negatives, you can feed them back in to improve the model.