Extract first non NAN value in an array
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I have a cell array of 10 or so elements, and the first few values are NaN. I want to display the first non NaN value in the column and assign it to a variable. For Example:
A = {NaN; NaN; NaN; NaN; 1; 2; 3; 4; 6; 8};
B = 'first non NaN value'
Any quick one liners to pull this value?
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Star Strider
2017-6-22
See if this does what you want:
B = A(find(cellfun(@(x)~isnan(x), A) == 1, 1))
5 个评论
Paxton Carnes
2017-6-22
Star Strider
2017-6-22
That’s essentially the same code. It’s easier, since it doesn’t need the cellfun function:
A = [NaN; NaN; NaN; NaN; 1; 2; 3; 4; 6; 8];
B = A(find(~isnan(A) == 1, 1))
Paxton Carnes
2017-6-22
+1. And you do not need an anonymous function:
B = A{find(~cellfun(@isnan, A), 1)}
Anonymous functions in cellfun are slower than function handles.
A = num2cell(rand(1, 1000));
tic; for k=1:100; B=A{find(cellfun(@(x)~isnan(x), A)==1, 1)}; end; toc
tic; for k=1:100; B=A{find(~cellfun(@isnan, A), 1)}; end; toc
Elapsed time is 0.663674 seconds.
Elapsed time is 0.146717 seconds.
In addition, the code is leaner, such that there are less chances for typos ;-)
Star Strider
2017-6-22
@Paxton Carnes — My pleasure!
@Jan — Noted. Thank you for the vote! (The anonymous function was part of an initial experiment. I forgot to simplify it in my final Answer for the cell, but did in my code for the vector.)
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