indexing a loop to run through multiple files

2021 7 7
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更新时间：2021 7 7
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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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Yongjian Feng
Yongjian Feng 2021-7-7

0 个投票

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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C.G.
C.G. 2021-7-7
编辑：C.G. 2021-7-7
Thankyou for your response.
I have tried the sort function you use but it doesnt sort my files into the correct order, it has done 1,10,11... etc.
Also I ran your code and it is still telling me that a is 1, when num_files is 40. This is what it was doing when I tried myself
Yongjian Feng
Yongjian Feng 2021-7-7
I see. Just a small mistake there.
%% 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: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
C.G.
C.G. 2021-7-7
Thank you that works for me now.
Just another question, but in each iteration of the loop I want the variable GTav to save so I can plot this up. Is there a way to save this value each time?
Yongjian Feng
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
C.G.
C.G. 2021-7-7
Thank you for your help!

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