indexing - Which inputs produced the ith output of outer in R? -

r has function outer allows compute function every combination of inputs xs , ys, e.g.:

xs <- 1:5 ys <- 0:10 zs <- outer(xs, ys, vectorize(function(x, y) sin(x) + y**2)) 

let's want know minimal value in zs:

> min(zs) [1] -0.9589243 

and position it's in:

> which(zs==min(zs)) [1] 5 

now how can figure out x of xs , y of ys produced 5th z of zs?

i can recompute using outer(xs, ys, vectorize(function(x, y) paste(x,y)))[which(zs==min(zs))] string of indices, seems bloody inefficient me. what's better way?

you have use:

which(zs==min(zs), arr.ind=t) #     row col #[1,]   5   1