I am trying to learn what AP (average precision) means and I came across this page: https://towardsdatascience.com/breaking-down-mean-average-precision-map-ae462f623a52
Here is the given formula:
And here is the given example:
This is a little intuitive to be to set the numerator at all red crossed images (false positives) to 0, because at these points, TP seen in the formula is bigger than 0 -- in the 2nd and 3rd predicted positives (which are false) TP seen so far is 1, and in the 6th predicted positive (which is also false), TP is 3. Then why the author used 0 as "TP seen" for them?