# Averaging values within bins

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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 CommentsShow 1 older commentHide 1 older comment
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 on 28 Oct 2018
"Would the histogram function help nevertheless?"
Yes, because they can also return the indices.

Bruno Luong on 28 Oct 2018
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')
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 on 13 Jun 2022
keep = isfinite(x) & isfinit(y);
x = x(keep);
y = y(keep);
... do the rest
Make sure the extrem edges cover entirely your data.

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.