How to get the maximum consecutive NaNs for each column

Question

Tiago Dias am 26 Apr. 2018

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https://de.mathworks.com/matlabcentral/answers/397553-how-to-get-the-maximum-consecutive-nans-for-each-column

Kommentiert: ARCHANA MAJHI am 15 Mai 2020

Akzeptierte Antwort: Ahmet Cecen

In MATLAB Online öffnen

Hello,

So i got a matrix A with 2 columns and 10 rows for example, with numbers and NaN's:

A =

     1     2
     3     4
   NaN   NaN
   NaN     7
     8     9
   NaN   NaN
     0   NaN
     9   NaN
   NaN   NaN
   NaN     8

I want to calculate for each column of A the maximum number of consecutive NaN's, so the result would be like

result = [2 4]

I saw this code for a vector, but in my case since i got multiple columns doesnt quite do what i want

nanLocations = isnan(A) % Get logical array of whether element is NaN or not.
props = regionprops(nanLocations, 'Area', 'PixelIdxList'); % Find all the regions.
% DONE!  Now let's print them out
for k = 1 : length(props)
  fprintf('Region #%d has length %d and starts at element %d and ends at element %d\n',...
    k, props(k).Area, props(k).PixelIdxList(1), props(k).PixelIdxList(end));
end

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Answer 1

Ahmet Cecen am 26 Apr. 2018

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Direkter Link zu dieser Antwort

https://de.mathworks.com/matlabcentral/answers/397553-how-to-get-the-maximum-consecutive-nans-for-each-column#answer_317338

In MATLAB Online öffnen

Here you go:

result = zeros(1,size(A,2));
for i = 1:size(A,2)
    B = isnan(A(:,i));
    CC = bwconncomp(B);
    Sizes = cellfun(@length, CC.PixelIdxList);
    result(i) = max(Sizes);
end