Error in the roc function?

[youngjaewoo]

Hi, I don't think roc function is working properly. Here's an example.

gt = [1,2,1,2,1,2,1,2,1,2]
pr = [1,1,1,1,1,1,1,1,1,1]
roc(gt, pr)

This produces

p = 10
n = 0
tp = 5
tn = 0
fp = 0
fn = 0

Above don't look right to me. Or perhaps, I'm using it wrongly in which updated documentation would be useful. The current documentation says,

roc(gt::AbstractArray{T,1} where T<:Integer, pr::AbstractArray{T,1} where T<:Integer) in MLBase at /Users/youngjaewoo/.julia/v0.6/MLBase/src/perfeval.jl:162

[laborg]

I stumbled over this too. It's not an error, just poor documentation. If you look at the code at

MLBase.jl/src/perfeval.jl

Line 141 in ded7174

if _ispos(gi) # gt = true

you see its only working for binary input (binary here meaning value 0 or 1 for either ground truth or prediction).