How to select several intervals from a vector?

Y=1:2:30;
intervals=[1,3;...
           11,15];
Y(cell2mat(arrayfun(@(A,B) A:B, intervals(:,1)', intervals(:,2)', 'uniform', 0)))
ans = 1x8
     1     3     5    21    23    25    27    29
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Csaba 2024-4-26，9:52

OK, this works. Thank you!

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Answer 2

DGM 2021-11-26

0
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https://ww2.mathworks.cn/matlabcentral/answers/1596844-how-to-select-several-intervals-from-a-vector#answer_841289

编辑：DGM 2021-11-26

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Idk. Here's three ways. They all use loops. Is there something more elegant? Prrrrobably. Is it faster? Probably depends. I'm sure there's more to be said about the topic. I'll leave that for others.

A = rand(1,1000);
bex = randi([1 1000],50,2);
timeit(@() loopappending(A,bex))
ans = 1.9935e-04
timeit(@() loopindexing(A,bex))
ans = 1.5171e-04
timeit(@() loopcell(A,bex))
ans = 1.1135e-04
% simply append subvectors
function B = loopappending(A,bex)
    B = [];
    for b = 1:size(bex,1)
        B = [B A(bex(b,1):sign(diff(bex(b,:))):bex(b,2))];
    end
end
% preallocate and use direct indexing
function B = loopindexing(A,bex)
    B = zeros(1,sum(abs(diff(bex,1,2))+1)); % preallocate
    endpoints = [0; cumsum(abs(diff(bex,1,2))+1)];
    for b = 1:size(bex,1)
        B(endpoints(b)+1:endpoints(b+1)) = A(bex(b,1):sign(diff(bex(b,:))):bex(b,2));
    end
end
% throw output into cell array and then rearrange
function B = loopcell(A,bex)
    B = cell(1,size(bex,1));
    for b = 1:size(bex,1)
        B{b} = A(bex(b,1):sign(diff(bex(b,:))):bex(b,2));
    end
    B = horzcat(B{:});
end