indexing a loop to run through multiple files

Question

C.G. 2021-7-7

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/873888-indexing-a-loop-to-run-through-multiple-files

评论： C.G. 2021-7-7

I have experimental data in multiple csv files.

Ive written the code I want and checked this works by only inputting 1 specific file, but now I am trying to write in a loop to do the same for all the files. I am struggling with the indexing to get this to work, could anybody help?

%% input csv files
file = dir('*.csv'); %read the files into matlab
num_files = length(file); %record how many files have been found
[~, index] = natsort({file.name}); %sort the files into order
filelist = file(index);
%% Calculate granular temperature 
for a = 1:length(num_files)
%read the table into matlab
table = table2array(readtable(filelist(a).name));
%save the particle ID's and velocity components
T = table(:, [1:4]);
%calculate resultant velocity for each particle (sqrt of the velcoities squared)
ResV = sqrt((T(:,2).^2) + (T(:,3).^2) + (T(:,4).^2));
%calculate mean resultant velocity of all the particles
ResVav = mean(ResV)
%calculate the average granular temperature 
GTav = mean(ResV-ResVav)
end 

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Answer 1

Yongjian Feng 2021-7-7

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https://ww2.mathworks.cn/matlabcentral/answers/873888-indexing-a-loop-to-run-through-multiple-files#answer_741833

Try this:

%% input csv files
file = dir('*.csv'); %read the files into matlab
num_files = length(file); %record how many files have been found
sorted = sort({file.name});
for a = 1:length(num_files)
%read the table into matlab
table = table2array(readtable(sorted{a}));
%save the particle ID's and velocity components
T = table(:, [1:4]);
%calculate resultant velocity for each particle (sqrt of the velcoities squared)
ResV = sqrt((T(:,2).^2) + (T(:,3).^2) + (T(:,4).^2));
%calculate mean resultant velocity of all the particles
ResVav = mean(ResV)
%calculate the average granular temperature 
GTav = mean(ResV-ResVav)
end 

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Yongjian Feng 2021-7-7

编辑：Yongjian Feng 2021-7-7

Yes. Try this:

%% input csv files
file = dir('*.csv'); %read the files into matlab
num_files = length(file); %record how many files have been found
sorted = sort({file.name});
result = [];
for a = 1:num_files
%read the table into matlab
table = table2array(readtable(sorted{a}));
%save the particle ID's and velocity components
T = table(:, [1:4]);
%calculate resultant velocity for each particle (sqrt of the velcoities squared)
ResV = sqrt((T(:,2).^2) + (T(:,3).^2) + (T(:,4).^2));
%calculate mean resultant velocity of all the particles
ResVav = mean(ResV)
%calculate the average granular temperature 
GTav = mean(ResV-ResVav);
result(end+1) = GTav;
end 
result