How to calculate 11 point interpolated standard recall precision? [closed]

Question

I am actually not sure about the recall = 0 and recall = 1. I am trying to draw the recall vs precision curve. Interpolation is taking the max precision between two standard recall level. I am explaining- when I am drawing the recall vs precision curve,

max precision between 0.0 ~ 0.1 will be drawn at recall 0.
max precision between 0.1 ~ 0.2 will be drawn at recall 0.1.
max precision between 0.2 ~ 0.3 will be drawn at recall 0.2.
...
max precision between 0.9 ~ 1.0 will be drawn at recall 0.9.

then what will be the value at recall 1.0?

If I started assigning precisions from recall 0.1 then what will be the precision at recall 0?

In some cases I have seen at recall 0 precision is 1 but did not get any explanation. For average precision its not 1. Not getting any explanation.

It is a interpolated recall-precision curve. What will be the precision at recall 1? I have 11 recall value in x-axis but 10 precision value for y-axis. so, how to draw the curve?

Answer 1

The simplest thing would be to use linear extrapolation from the previous two points.

But you really have limited idea from the data, and one can do the extrapolation by eye easily enough. If you aren't going to really use the value, but are just trying to complete the figure, I would just leave it out and do the plot within the range of the data, as you've done.