Piece-wise linspace

Question

Toze 2012-1-30

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/27468-piece-wise-linspace

采纳的回答： Jan

Hi

I need to generate a vector (0's and 1's), when I'm given indices for the starting and endpoints of the 1's trains.

Example: m=zeros(1,10); starts=[1 5 9]; ends=[3 6 9];

the generated vector should be [1 1 1 0 1 1 0 0 1 0]

Any way of avoiding a loop? [starts(:):ends(:)] only looks at the first entry of the source vectors...

thanks Tozé

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Answer 1

Jan 2012-1-30

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在 MATLAB Online 中打开

Do the sections overlap? If not, try this:

m         = zeros(1, 10);
starts    = [1 5 9];
ends      = [3 6 9];
m(starts) = 1;
m(ends)   = -1;
m         = cumsum(m);

If they sections are overlapping:

m         = zeros(1, 10);
p         = zeros(1, 10); 
starts    = [1 5 9];
ends      = [3 6 9];
m(starts) = 1;
m(ends)   = -1;
m         = cumsum(m);
p(m > 0)  = 1;

I cannot test this currently, so please keep care.

And perhaps this helps: FEX: interval merging.

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Answer 2

Bjorn Gustavsson 2012-1-30

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Why bother searching for a cunning loop-free version (non-explicit) when the looped version is so straightforward? How much time does it take to come up with something clever compared to the potential gain in run-time?

HTH,