Replace missing elements in an array with NaN

Question

Anantha Padmanabhan 2016-10-4

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https://ww2.mathworks.cn/matlabcentral/answers/305671-replace-missing-elements-in-an-array-with-nan

编辑： Thorsten 2016-10-4

Hello! for i=1:n

            scanindex = round((i-1)*pointsperscan+1):round(i*pointsperscan);
           filterindex == (i-1)*pointsperscan+find(vlos(scanindex)<=blade_flicker_threshold&...
                          quality(scanindex)>=quality_range(1)&...
                          quality(scanindex)<=quality_range(2)&...
                          power(scanindex)>=power_range(1)&...
                          power(scanindex)<=power_range(2))';

So i have this code. Scan index reads the entire second values with 312 entries and the filterindex filters based on the scan parameters which results in an array less than 312 entries. I want to keep the size of the filterindex same as the scanindex as I need to rewrite the code for more general purposes and so I was thinking if there was a way to replace the indeces which do not match the filter parameters with NaN values. So the output should read that the size of scanindex and the filterindex are the same!

Thanks

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Answer 1

Thorsten 2016-10-4

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You can add the needed number of NaNs to the filterindex;

filterindex(end+1:numel(scanindex) = NaN;

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Anantha Padmanabhan 2016-10-4

Hey, What you say will just add NaNs to the end of the filterindex. I want to have NaNs in the particular index in the filterindex when compared to the scan index. So if scanindex(25) does not satisfy the conditions specified, filterindex(25) must be a NaN.

Thorsten 2016-10-4

编辑：Thorsten 2016-10-4

在 MATLAB Online 中打开

I see. I think that you can use logical indexing to solve your problem:

filterindex = nan(size(scanindex));
fi = (i-1)*pointsperscan+find(vlos(scanindex)<=blade_flicker_threshold&...
                        quality(scanindex)>=quality_range(1)&...
                        quality(scanindex)<=quality_range(2)&...
                        power(scanindex)>=power_range(1)&...
                        power(scanindex)<=power_range(2))'; 
filterindex(fi) = true;