how to obtain the id of change in vector

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Niraj 2012-11-27

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https://ww2.mathworks.cn/matlabcentral/answers/54906-how-to-obtain-the-id-of-change-in-vector

i have a vector say

v =[ 0 0 0 0 28 34 0 56 67 0 0 0 69 71 75 89 90 0]

I need to find what are the ids where there is change in value from 0 to some number or from some number to 0. So in this case the ids should be like 5 6 8 9 13 17

Is there a smart way to do it?

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回答（2 个）

Walter Roberson 2012-11-27

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https://ww2.mathworks.cn/matlabcentral/answers/54906-how-to-obtain-the-id-of-change-in-vector#answer_66633

在 MATLAB Online 中打开

Lv = (v ~= 0);
find( Lv(1:end-1) ~= Lv(2:end) )

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Jan 2012-11-27

I assume "id" means "index".

Niraj 2012-11-27

yes,"id" means "index".

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Jan 2012-11-27

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https://ww2.mathworks.cn/matlabcentral/answers/54906-how-to-obtain-the-id-of-change-in-vector#answer_66636

编辑：Jan 2012-11-27

在 MATLAB Online 中打开

Lv = (v ~= 0);
Index = find(diff(Lv)) + 1;

[EDITED]

Lv    = [false, (v ~= 0), false];
ini   = strfind(Lv, [false, true]) + 1;
fin   = strfind(Lv, [true,  false]);
Index = reshape([ini(:), fin(:)], 1, []);