Having trouble understanding normalized rank calculation
Opened this issue · 1 comments
rushabh31 commented
I read all the instruction and vignettes available for precrec package, but I am having trouble understanding, how normalized rank is being calculated for basic mode. It would be really helpful, if you can include small introduction or explanation about it in the documentation or here.
I am looking forward for your reply.
Great work!!
Thank you.
takayasaito commented
Hi,
Normalized ranks are calculated as (ranks - 1)/(n - 1)
. Below is an example of R code to calculate normalized ranks in precrec
.
> ranks <- c(3, 2, 1, 4)
> ranks
[1] 3 2 1 4
>
> n <- length(ranks)
> n
[1] 4
>
> (ranks - 1) / (n - 1)
[1] 0.6666667 0.3333333 0.0000000 1.0000000
Please notice the ranks
in the example above are given higher ranks (as 1 is the best rank) for higher scores. It is different from the default R rank
function.
> scores <- c(20, 75, 100, 1)
>
> # R's default rank function
> rank(scores)
[1] 2 3 4 1
>
> # precrec's rank function
> precrec::.rank_scores(scores)$ranks
[1] 3 2 1 4