# mean calculation by comparison

2 views (last 30 days)
Commented: Mohammad Abouali on 25 Apr 2015
Hi, In the following vectors, I need to get the "mean" of y values for each set of similar x values. What I mean is I need the avg of Y for each group of x. I also need to save those mean Y values.
x=[3 3 3 4 4 5 5 5 5 3 11]; y=[1 2 4 5 7 1 1 8 10 10 1];

Star Strider on 25 Apr 2015
Edited: Star Strider on 25 Apr 2015
This looks like an application for accumarray:
x=[3 3 3 4 4 5 5 5 5 3 11];
y=[1 2 4 5 7 1 1 8 10 10 1];
y_means = accumarray(x', y, [], @mean);
EDIT:
To get a summary of the x-values (first column) and the corresponding y_means values (second column:
xu = unique(x);
ys_means = [xu' y_means(xu)]
produces:
ys_means =
3 4.25
4 6
5 5
11 1
Mohammad Abouali on 25 Apr 2015
Well, updated the answer, to include both start and end index of the block, as well as x-new.
As star strider mentioned, my answer on the other post is solving the same problem but using a different approach.

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