Help with isnan with two matrices of unequal dimensions

Question

Sayantan Sahu 2018-1-15

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https://ww2.mathworks.cn/matlabcentral/answers/377229-help-with-isnan-with-two-matrices-of-unequal-dimensions

回答： Guillaume 2018-1-16

采纳的回答： Guillaume

Hi,

I have two matrices of unequal dimensions. pol1 = 1 x 22648 and pol2 has dimensions of 1 X 22706.

I wanted to plot one against the other and I want to check the cells for which both values exist.

I tried good_use=find(~isnan(pol1) & ~isnan(pol2))

but I get an error ' Matrix dimensions must agree '.

How do I solve this error ?

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Guillaume 2018-1-15

在 MATLAB Online 中打开

"I want to find the indices for which both pol1 and pol2 have values"

You still haven't explained what that means when the two vectors have different length. Using shorter vectors, if

pol1 = [1   nan 2 nan]
pol2 = [nan 3   4 nan  nan 5]

what result would you expect ?

Sayantan Sahu 2018-1-16

yes use shorter vectors. In the example you provide, it should plot pol1(3) and pol2(3) and so on. To summarize wherever its numeric values not NaN.

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Answer 1

Guillaume 2018-1-16

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在 MATLAB Online 中打开

"yes use shorter vectors"

So in effect, you're telling us to truncate the longer one so that it is the same length as the other? If you do that then your initial expression will work.

%truncate longer vector to the size of the shorter vector:
veclength = min(numel(po1), numel(pol2));
pol1 = pol1(1:veclength); 
pol2 = pol2(1:veclength);
%your original search, find not needed
good_use = ~isnan(pol1) & ~isnan(pol2)
%plot
plot(pol1(good_use), pol2(good_use))