What does recall mean in Machine Learning?

Question

I know that the meaning of recall in search engine, but what\'s the meaning of recall of a classifier, e.g. bayes classifier? please give a an example, thanks.

for examp

Answer 1

Recall literally is how many of the true positives were recalled (found), i.e. how many of the correct hits were also found.

Precision (your formula is incorrect) is how many of the returned hits were true positive i.e. how many of the found were correct hits.

It's pretty straightforward, actually.