How to create groups by using labels?

V = [ 1 2 3 4 5 6 7 8];
L = { 'A', 'A', 'A', 'C', 'C', 'C', 'A', 'B' };
[tf,loc] = ismember(L,unique(L));
for ni = 1:max(loc)
    VV{ni} = V(loc==ni)
end

Note that I used a cell array to store the output, rather than the alphabetic sequence variables.

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Jim 2019-10-4

Thank you very much!

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Answer 2

Daniel M 2019-10-4

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https://ww2.mathworks.cn/matlabcentral/answers/483668-how-to-create-groups-by-using-labels#answer_394889

编辑：Daniel M 2019-10-4

I don't recommend making variables dynamically for various reasons, but making a struct is fine to do, and can even make fieldnames dynamically:

[uL,~,iL] = unique(L);
for f = 1:length(uL)
    s.(uL{f}) = V(iL==f);
end

The output struct s will have fieldnames that are the same as the labels in L.

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Jim 2019-10-8

This doesnt work if the labels are numbers.

Do you have any idea how to make it work for numberlabels aswell?

Daniel M 2019-10-8

Well, how would you have done it manually? In your original post you wanted to make variables named A = [1 2 3 7], etc. How would you have done it if the label was a number instead?

You can try prepending a letter before any labels that start with numbers.

L = {'A','A','B','2','C','1','x1','1x'}
s = ~cellfun(@isempty, regexp(L,'^\d'),'UniformOutput',true) % finds the labels that start with a number
L(s) = cellfun(@(x) ['n',x],L(s),'UniformOutput',false); % preprend with the letter n
L

with output

L =
  1×8 cell array
    {'A'}    {'A'}    {'B'}    {'2'}    {'C'}    {'1'}    {'x1'}    {'1x'}
    
s =
  1×8 logical array
   0   0   0   1   0   1   0   1
   
L =
  1×8 cell array
    {'A'}    {'A'}    {'B'}    {'n2'}    {'C'}    {'n1'}    {'x1'}    {'n1x'}