Syntax

IDX = kmeans(X,k)
[IDX,C] = kmeans(X,k)
[IDX,C,sumd] = kmeans(X,k)
[IDX,C,sumd,D] = kmeans(X,k)
[...] = kmeans(...,param1,val1,param2,val2,...)



Description

IDX = kmeans(X,k) partitions the points in the n-by-p data matrix X into k clusters. This iterative partitioning minimizes the sum, over all clusters, of the within-cluster sums of point-to-cluster-centroid distances. Rows of X correspond to points, columns correspond to variables. kmeans returns an n-by-1 vector IDX containing the cluster indices of each point. By default, kmeans uses squared Euclidean distances. When X is a vector, kmeans treats it as an n-by-1 data matrix, regardless of its orientation.
[IDX,C] = kmeans(X,k) returns the k cluster centroid locations in the k-by-p matrix C.
[IDX,C,sumd] = kmeans(X,k) returns the within-cluster sums of point-to-centroid distances in the 1-by-k vector sumd.
[IDX,C,sumd,D] = kmeans(X,k) returns distances from each point to every centroid in the n-by-k matrix D.
[...] = kmeans(...,param1,val1,param2,val2,...) enables you to specify optional parameter/value pairs to control the iterative algorithm used by kmeans. Valid parameter strings are listed in the following table.