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NB
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Calculate mean values of specific (but dynamic) intervals

Asked by NB
on 1 Aug 2019
Latest activity Commented on by NB
on 2 Aug 2019
Hello everyone,
I want to calculate mean values of specific (but dynamic) intervals across several result files. I know how I get more than one results file into MATLAB and the other basics.
But what I dont know is the following: an interval should be defined/ starting when a value is between -0.05 and 0.05 in a specific column. It is dynamic, because it sometimes lasts for 8 seconds, sometimes for 10 seconds. So the interval should be ended when the value is <-0.05 or >0.05.
Then i want to calculate the mean value of data from another column according to the defined intervals in the other column.
I hope u understand what I want to do.
Thanks in advance

  7 Comments

I presumed as much...one last Q? (at least last for now..."one more thing!" :) ) -- is that it will cross again a sure thing and it is only the initial time period within the threshold around zero that is of interest, correct? So one can truncate anything after the transient portion begins once it again at some distant time crosses the threshold? If that is so, then it makes the search logic much simpler.
well it will cross it several times (roughly 20-25 times) so there are 20-25 intervals that are of interest and which has to be defined. so unfortunately u cant truncate something
Ah! That's a key piece, then...

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1 Answer

Answer by Jos (10584)
on 1 Aug 2019
 Accepted Answer

% interval and value are the relevant columns of your data matrix
interval = data(:,3)
value = data(:,2)
% find the sections
q = ~(interval < -.05 | interval > .05)
dq = diff([false q false])
ix1 = find(dq==1)
ix2 = find(dq == -1) - 1
% function to apply to each section
myfun = @(k) mean(value(ix1(k):ix2(k)))
R = arrayfun(myfun, 1:numel(ix1)) % mean of each section
not tested but it should work :-)

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