How to find prior value to NaN without terminating the loop?

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Ivan Shorokhov 2015-1-27

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https://ww2.mathworks.cn/matlabcentral/answers/172537-how-to-find-prior-value-to-nan-without-terminating-the-loop

编辑： Ivan Shorokhov 2015-2-2

Dear all,

I have following code, which I'm using to find value before NaN. For example I have following vector N=[1 2 3 4 NaN NaN], so I'm looking for value 4, which is before NaN.

And I wondering, is there any other way how I can store only first needed value without terminating it? I have tried to make an array and extract only the first value but it didn't work:

So I simply want to find prior value to NaN without terminating the loop.

Thanks for any help,

I

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Answer 1

Star Strider 2015-1-27

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https://ww2.mathworks.cn/matlabcentral/answers/172537-how-to-find-prior-value-to-nan-without-terminating-the-loop#answer_166097

在 MATLAB Online 中打开

I would do this:

N=[1 2 3 4 NaN NaN];
Idx = find(isnan(N), 1, 'first')-1;     % Index Of Element Before First ‘NaN’
BeforeNaN = N(Idx)                      % Value Of Element Before First ‘NaN’

I created ‘Idx’ separately for clarity, but the two statements could be combined as one if you want to.

The code produces: