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Averaging values within bins

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MiauMiau
MiauMiau on 28 Oct 2018
Commented: Bruno Luong on 13 Jun 2022
Hi,
I have the two arrays x and y (attached), which I plot with plot(x,y). This is creating "bins" of width 5:
What is the fastest way to average the values within each such bin, such that we end up with one value/bin, especially if we don't want to pre-define bin width?
Thanks
  3 Comments
MiauMiau
MiauMiau on 28 Oct 2018
I don't want to have a histogram in the classical sense: I want the mean value within a bin (not the count). Would the histogram function help nevertheless?
Stephen23
Stephen23 on 28 Oct 2018
"Would the histogram function help nevertheless?"
Yes, because they can also return the indices.

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Answers (2)

Bruno Luong
Bruno Luong on 28 Oct 2018
load('y.mat')
load('x.mat')
plot(x,y)
edges = (0:5:50);
[~,~,loc]=histcounts(x,edges);
meany = accumarray(loc(:),y(:))./accumarray(loc(:),1);
xmid = 0.5*(edges(1:end-1)+edges(2:end));
figure
plot(x,y)
hold on;
plot(xmid,meany,'r')
  2 Comments
AnnieLieseMari
AnnieLieseMari on 13 Jun 2022
Hi there!
I'm working with a very similar data set and need some help with my code. I know this was posted and answered a while ago, but I would really appreciate the help.
After using the same code you provided, but with my data set and edges of (4.25:0.5:17.75), I am getting an error saying "First input SUBS must contain positive integer subscripts."
I have a data set of x and y values that is upwards of 2000+ data points. It's super big and when I zip it, the Help Center is still saying it's too big. Please let me know if you'd like me to provide a sample of maybe 20 or so data points to help out.
I think the main reason this is happening is that my data has NaN values in it. Though, I'm not sure how to remove those. Of course, if I remove the x values, I have to preserve the y values so the other pairs still match up.
Bruno Luong
Bruno Luong on 13 Jun 2022
Simply remove the bad data:
keep = isfinite(x) & isfinit(y);
x = x(keep);
y = y(keep);
... do the rest
Make sure the extrem edges cover entirely your data.

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Steven Lord
Steven Lord on 28 Oct 2018
Do you want to use histogram or histcounts to bin the data, or are you looking for something more of a moving average, where the value of the averaged signal at a particular time is the mean of the data for that time and some data points before and after that time? If the latter, see movmean.

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