Selection of priority data

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Giuseppe
Giuseppe 2014-12-26
回答： Giuseppe 2014-12-27
Hello,
I'm trying to solve a problem. I have a vector of data such as:
data=[3;4;8;NaN;NaN;NaN;7;4;3;NaN;NaN;2;3;NaN;9]
length of data can be variable and NaN value phases can happen everywhere within a vector.
I need to find the first NaN value and count the number of next NaN. However, I do not want to take into account any other NaN value after the first portion of NaN.
In this case my result would be: First NaN at raw 4. Three NaN values. I know how to use the function find, indeed this is the code I used as far:
findNaN = find(isnan(data));
The problem is that in that way I will get the others NaN too that I do not want to locate.
Any idea?
Thanks, Giuseppe

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采纳的回答

Shoaibur Rahman
Shoaibur Rahman 2014-12-27
data=[3;4;8;NaN;NaN;NaN;7;4;3;NaN;NaN;2;3;NaN;9];
findNaN = find(isnan(data));
first = findNaN(1);
numberNaN = 1;
for k = first+1:length(data)
if isnan(data(k))
numberNaN = numberNaN+1;
else break
end
end
first, numberNaN

更多回答（2 个）

Image Analyst
Image Analyst 2014-12-27
If you're lucky enough to own the Image Processing Toolbox, it's easy. Just find the nan's, label then, and count the number in the first group. Here is the code:
labeledVector = bwlabel(isnan(data)) % Find nan's and label.
numberOfNansInFirstGroup = sum(labeledVector == 1) % Count the # of elements in group #1
Giuseppe
Giuseppe 2014-12-27
thanks for helping to improve my code

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