Index number of k-means clusters

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Gabriel
Gabriel 2016-2-25
评论： wathiq dukhan 2019-7-26
Hi guys, I have a program that cluster some data and then calculate the optimized number of clusters.
I want to know how I can get the index number of each data so I can plot them separated in clusters
My code is the following:
%importar dados do excel
imp = xlsread('Academia.xlsx');
%%Loop Kmeans K clusters
k=20
CH=zeros(1,k);
SH=zeros(1,k);
DB=zeros(1,k);
SUB=zeros(1,k);
%
% for i=1:k
% CH{i}=0;
% SH{i}=0;
% DB{i}=0;
% end
% eva = evalclusters(x,clust,criterion)
for i=1:k
[idx,C]=kmeans(imp,i,'MaxIter',10000); %C=centroides
% Como pegar o valor de idx ?
eva = evalclusters(imp, idx, 'CalinskiHarabasz')
CH(1,i)=eva.CriterionValues
eva2 = evalclusters(imp, idx, 'Silhouette')
SH(1,i)=eva2.CriterionValues
eva3 = evalclusters(imp, idx, 'DaviesBouldin')
DB(1,i)=eva3.CriterionValues
end
CH(1,1)=0
% % Descobrir as diferenças entre os valores de CH
while i>1
SUB(1,i)=CH(1,i)-CH(1,i-1);
i=i-1;
end
SUB(1,1)=0
%Achar o pulo maximo entre os clusters para o valor de CH:
% cell2mat(SUB); %Converte para matriz
%SUB2=cell2mat(SUB)
[V,N]=max(SUB) % Por algum motivo está pulando a célula vazia e fornecendo valor incorreto
SH
%SHF=cell2mat(SH)
[V2,N2]=max(SH) %Valor mais próximo de 1
DB
%DBF=cell2mat(DB)
[V3,N3]=min(DB) %Valor mais próximo de 0
if (N==N2) && (N2==N3)
disp('CH=SH=DB')
N
N2
N3
i=N
% y=xlswrite('Academia_target.xlsx',M(1,i),'D1:D80')
elseif N2==N3
disp('SH=DB')
elseif N==N3
disp('CH=DB')
elseif N==N2
disp('CH=SH')
else
disp('Todas as métricas forneceram valores diferentes')
end
In this case I want to retrieve the idx from the clustering in 4 clusters which is the optimized on in my case ( the Excel file from which I take the data is attached to this question.
Thanks in Advance !
  2 个评论
jgg
jgg 2016-2-25
I'm unclear what the problem is here; idx is a vector corresponding to the cluster ID for each observation for your fitted cluster. Isn't that what you want?
Gabriel
Gabriel 2016-2-27
Hi jgg,
The thing is that each time the K-means runs (up to 20) the value of idx changes. And I only know which value "i" I need after the loop for is completed. So I need to store all of idx values and have a way to retrieve the value which corresponds to i=4 in this case.
I already tried using a variable R{i}=idx after the k-means but for some reason I receive a error message saying (Cell contents assignment to a non-cell array object.
Error in import_excelv4 (line 27) R{i}=idx

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回答（1 个）

wathiq dukhan
wathiq dukhan 2019-7-26
I would like a program to calculate the number of clusters by genetic algorithm and k-means.
  2 个评论
Walter Roberson
Walter Roberson 2019-7-26
http://www.mathworks.com/matlabcentral/answers/6200-tutorial-how-to-ask-a-question-on-answers-and-get-a-fast-answer
k-means itself must be passed the number of clusters to use; it is not able to calculate the number of clusters. However, there are algorithms that can be used that run k-means a number of times and take estimates of what the most likely number of clusters is under certain conditions.
wathiq dukhan
wathiq dukhan 2019-7-26
I need to use GA to calculate the number of clusters.

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