output of k means clusters "idx"

idx = kmeans(X,k)

idx means what ? i read description of function but i still confused

how i can use it

if i need to know the output of each cluster without plot

like cluster 1(4,6,7)

cluster 2(5,7,9)

Answer 1

[Walter Roberson]

idx will be a vector which has as many entries as there are rows in X.

The j'th entry, idx(j) tells you the cluster number that X(j,:) belongs to.

which_in_cluster = cell(k,1);
for j = 1 : k
    which_in_cluster{j} = find(idx == j);
end

Now which_in_cluster will be a cell array in which the j'th entry is a vector indicating which rows were part of the j'th cluster.

[E]

Thank you so much It helps me understand.