algorithm - Contextual type for closure argument list expects 1 argument, but 2 were specified -

i'm trying algorithm working swift 2.1: http://users.eecs.northwestern.edu/~wkliao/kmeans/

though getting error on line:

  return map(zip2sequence(centroids, clustersizes)) { cluster(centroid: $0, size: $1) } 

here's full function:

func kmeans<t : clusteredtype>(         points: [t],         k: int,         seed: uint32,         distance: ((t, t) -> float),         threshold: float = 0.0001     ) -> [cluster<t>] {      let n = points.count     assert(k <= n, "k cannot larger total number of points")      var centroids = points.randomvalues(seed, num: k)     var memberships = [int](count: n, repeatedvalue: -1)     var clustersizes = [int](count: k, repeatedvalue: 0)      var error: float = 0     var previouserror: float = 0          repeat {             error = 0             var newcentroids = [t](count: k, repeatedvalue: t.identity)             var newclustersizes = [int](count: k, repeatedvalue: 0)              in 0..<n {                 let point = points[i]                 let clusterindex = findnearestcluster(point, centroids: centroids, k: k, distance: distance)                 if memberships[i] != clusterindex {                     error += 1                     memberships[i] = clusterindex                 }                 newclustersizes[clusterindex]++                 newcentroids[clusterindex] = newcentroids[clusterindex] + point             }             in 0..<k {                 let size = newclustersizes[i]                 if size > 0 {                     centroids[i] = newcentroids[i] / size                 }             }              clustersizes = newclustersizes             previouserror = error         } while abs(error - previouserror) > threshold          return map(zip2sequence(centroids, clustersizes)) { cluster(centroid: $0, size: $1) } } 

how change remove error?

as understand, trying to following:

return (0..<k).map { cluster(centroid: centroids[$0], size: clustersizes[$0]) } 

from swift's zip2sequence<sequence1, sequence2> documentation:

a sequence of pairs built out of 2 underlying sequences, elements of ith pair ith elements of each underlying sequence.

zip2sequence<[t], [int]> generator's element (t, int) tuple. can access individual elements of tuple index.

so, following code should work you:

return zip2sequence(centroids, clustersizes).map { cluster(centroid: $0.0, size: $0.1) }