# How to ignore certain columns in a matrix when calculating a mean across all columns in a matrix?

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Tomaszzz on 16 Mar 2022
Commented: Davide Masiello on 16 Mar 2022
Hi all,
I have a 100x16 double matrix (attached) which when plotted over one figure looks like this. Now, I want to calculate the mean across all columns in the matrix so that the output is a 100x 1 double. I can do this by following
figure
plot(S_or_z(:,1:8),'r')
hold on
plot(S_or_z(:,9:end),'b')
% get mean
S_or_z_meancycle = mean(S_or_z, 2);
However, when calcuating the mean, I would like ignore the columns indicated in red.
The rule that I would like to apply is that the columns which range (max-min) exceeds 200 should be ignored when calcuating the mean accross all columns.

Davide Masiello on 16 Mar 2022
Edited: Davide Masiello on 16 Mar 2022
See if this works
new_S_or_z = S_or_z(:,(max(S_or_z,[],1)-min(S_or_z,[],1)) < 200);
Unrecognized function or variable 'S_or_z'.
plot(new_S_or_z)
mean(new_S_or_z,[],2)
##### 2 CommentsShowHide 1 older comment
Davide Masiello on 16 Mar 2022
Yes, you're right! I got the syntax for "min" and "max" mixed up with the one for "mean", sorry about that.