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Asked by Jennifer on 7 May 2013

Hi, We have 100 .mat- data files containing 5 column vectors. We would like to calculate the average of the 4th column for each of those 100 .mat- data files. Here is a sample of one of our .mat-files:

0.6797 0.2551 0.2543 0.8308 0.0540 0.6551 0.5060 0.8143 0.5853 0.5308 0.1626 0.6991 0.2435 0.5497 0.7792 0.1190 0.8909 0.9293 0.9172 0.9340 0.4984 0.9593 0.3500 0.2858 0.1299 0.9597 0.5472 0.1966 0.7572 0.5688 0.3404 0.1386 0.2511 0.7537 0.4694 0.5853 0.1493 0.6160 0.3804 0.0119 0.2238 0.2575 0.4733 0.5678 0.3371

We tried the following code but we were not able to assign the 4th column the name “HR1” to calculate its mean for each person/.mat- data file.

%% Set path cd ('N:\backups\Jennifer T.\HR data analysis')

thePath.data = fullfile(pwd,'subject data','PTSDdata','to be added'); thePath.programs = fullfile(pwd,'programs');

addpath(genpath(thePath.data))

% Select multiple Out4 files and open them cd (thePath.data) [F,P]=uigetfile('*.*','MultiSelect', 'on'); Re=zeros(length(F),1); for i = 1:length(F) HR1=??(:,4); Re(i)= nanmean(HR1) End

Any suggestions on how to do this? Thank you!

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Answer by Walter Roberson on 7 May 2013

Accepted answer

http://matlab.wikia.com/wiki/FAQ#How_can_I_process_a_sequence_of_files.3F http://matlab.wikia.com/wiki/FAQ#How_can_I_create_variables_A1.2C_A2.2C....2CA10_in_a_loop.3F

Also, it is recommended to use the functional form of load:

data = load(F{i}); varnames = fieldnames(data); firstvar = varnames{1}; HR1 = data.(firstvar)(:,4);

Jennifer on 10 May 2013

Maybe you could also help us with this problem? ;-)

Thanks a lot!

Answer by Iman Ansari on 7 May 2013

Hi. What is the variable name that you want to calculate its 4th column average? if the name of the variable is the same in all files:

for i = 1:length(F) load(F{i}) HR1=Variable_name(:,4); Re(i)= nanmean(HR1); end

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