Get every first value above a treshold out of an array

Question

Mike Mierlo van 2019-12-8

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/495588-get-every-first-value-above-a-treshold-out-of-an-array

评论： Mike Mierlo van 2019-12-9

采纳的回答： dpb

在 MATLAB Online 中打开

Hi guys, Lets say I have an array with elements with

A = [1 2 3 4 5 6 2 3 4 5 6 3 4 5 6 7 8 1 2 1 2 1 2 3 4 5 6]

Now I want to have only the first values that are above the treshold 4.5 when reading from left to right. So reading from left to right when an element is lower than 4.5 it is a 0, when it is higher than 4.5, only the first element is a 1. When the next element is also higher than 4.5 it should be a zero. Only when the value of an element drops below 4.5 the next element above 4.5 should again be a one.

The result should be:

B = [0 0 0 0 1 0 0 0 0 0 1 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 1 0]

Please help me with the magic between A and B.

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Image Analyst 2019-12-8

Is this homework (it looks like it)?

Mike Mierlo van 2019-12-9

Hi. It is not homework. It is a simplified array. The actual array contains measurements of degradation of a component. This fails at a certain treshold. After that a new component is build in. The acutal array is way to big to share here, so I asked the question with a simplified code. I am going to try to fix it with the hints. If not, I'll be back.

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Answer 1

dpb 2019-12-8

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链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/495588-get-every-first-value-above-a-treshold-out-of-an-array#answer_405447

编辑：dpb 2019-12-9

在 MATLAB Online 中打开

B=([0 diff((A>trsh)-1)]==1);

For comparison,

>> [A;B]
ans =
 Columns 1 through 27
 1  2  3  4  5  6  2  3  4  5  6  3  4  5   6   7   8   1   2   1   2   1   2   3   4  5  6
 0  0  0  0  1  0  0  0  0  1  0  0  0  1   0   0   0   0   0   0   0   0   0   0   0  1  0
  >> 