Sum five elements before a specific number

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Karoline Qasem
Karoline Qasem 2017-7-17
评论： Karoline Qasem 2017-7-18
Hi, I used "findpeaks" to find the IDs of all the peaks in my data. I need for each peak to find the average of five elements before it. the problem is that some of the peaks don't have five elements before it (say the second value is a peak, therefore, there is only one value before it). How can I tell matlab to average whatever is available but not more than 5 elements?
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Image Analyst
Image Analyst 2017-7-18
编辑：Image Analyst 2017-7-18
Please attach your data. I'm puzzled as to why your indexes are not in ascending order. I need to see the data to learn why. When I run it, ID always has increasing index values. In the meantime, check out movmean() to get a filtered vector, then pick out the values of the filtered array at those indexes.
Karoline Qasem
Karoline Qasem 2017-7-18
编辑：Walter Roberson 2017-7-18
The data is very huge and messy. The reason why it is going decending is because I used this:
NP=6;
[pks,ID]= findpeaks(Q,'NPeaks',NP,'SortStr','descend');

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Walter Roberson
Walter Roberson 2017-7-18
data_before = Yourdata(max(1, idx-5) : idx-1)
Note that in the case that idx is 1, this will give the empty result, as "empty" is all of the data that is available before the location.
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Walter Roberson
Walter Roberson 2017-7-18
编辑：Walter Roberson 2017-7-18
T = [nan(5,1); X(:)];
lenT = length(T);
idx = sub2ind([lenT, 1], 5+bsxfun(@plus, ID, -5:-1), ones(length(ID), 5));
result = nanmean( T(idx), 2 );

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