algorithm - How to draw a precision-recall diagram? -

precision , recall metrics evaluation algorithms, , defined this:

precision = true_positive / (true_positive + false_positive)  recall = true_positive / (true_positive + false_negative) 

so, think every algorithm have 1 number precision , 1 number recall, see there diagram evaluating according precision , recall, want know how can draw diagram 1 point?(one precision , 1 recall every algorithm)

you draw histogram precision , recall each algorithm. it's still bit difficult read because each algorithm there 2 values. need decide important characteristics: recall or precision?

have considered using f-measure tries combine both measures? http://en.wikipedia.org/wiki/f1_score

edit:

my suggestion use histogram:

but solution plot this:

both done using libreoffice.