Want to see the results from the 79 csv files but only getting one result

Hi,

I would like to read 79 the csv files in the folder then want to read the column_13 from all the csv files hence take the mean of column_13 from each csv files hence will give me 79 mean values hence further use the relation below

TurbulentFluctuation_Square = (TurbulentFluctuation_array).^2;     % taking the square of the array of each array from each folder
TurbulentFluctuationSquare_Mean = mean(TurbulentFluctuation_Square); %taking the mean of the sqaure value
TurbulentStrength_Urms = sqrt(TurbulentFluctuationSquare_Mean)        % sqrt of the mean value
Turbulent_Intensity = TurbulentStrength_Urms*(sqrt(TurbulentFluctuationArray_Mean)); % calculating turbulent intensity

To calculate them values from each mean values and save it into the new csv file but I am struggling to make a code. I made a code to read one file and it is working fine. But the code to work for all the csv file also giving me one result. Code is below if you can help please!

Code:

close all; clear all; clc;

P = 'F:\3-PIV_Experimental_Data\Calculations_TurbulentIntensity\line_Data\Elliptical_Side\Length\DesignPoint\110_outlet';
Q = 'F:\3-PIV_Experimental_Data\Calculations_TurbulentIntensity\line_Data\Elliptical_Side\Length\DesignPoint';
S = dir(fullfile(P,'*.csv'));
N = natsortfiles({S.name});
% Pre-allocate output vector
ranges = zeros(numel(N), 1);
% loop over the file names
for idx = 1:numel(N,1);
    data = readtable( fullfile(P, N{idx}) ); % read the csv files
    col_13 = data(:,13);     % Get the 13th column
    TurbulentFluctuation_array = table2array(col_13)  %convert the table to arrays
    
    TurbulentFluctuationArray_Mean = mean(TurbulentFluctuation_array); %calculate the mean of each array from each folder
    
    TurbulentFluctuation_Square = (TurbulentFluctuation_array).^2;     % taking the square of the array of each array from each folder
    TurbulentFluctuationSquare_Mean = mean(TurbulentFluctuation_Square); %taking the mean of the sqaure value
    
    TurbulentStrength_Urms = sqrt(TurbulentFluctuationSquare_Mean)        % sqrt of the mean value
    
    Turbulent_Intensity = TurbulentStrength_Urms*(sqrt(TurbulentFluctuationArray_Mean)); % calculating turbulent intensity 
end   


csvwrite(fullfile(Q, 'output.csv'), TurbulentFluctuationSquare_Mean, TurbulentStrength_Urms,Turbulent_Intensity); % its only saving first term value TurbulentFluctuationSquare_Mean

[Andriy Voshchenko]

You are overwriting the result at each iteration. Try predefining the results matrix (if you know the final dimensions, if not you can skip this and matlab will automatically change the dimensions in each iteration, it will be less optimized but still works)

TurbulentStrength_Urms=zeros(N,1); % matrix of results that you will fill later in your "for cycle"

Inside your "for" loop change the results to the following:

   TurbulentFluctuationArray_Mean(idx) = mean(TurbulentFluctuation_array); 
    
    TurbulentFluctuation_Square(idx) = (TurbulentFluctuation_array).^2;    
    TurbulentFluctuationSquare_Mean(idx) = mean(TurbulentFluctuation_Square(idx)); 
    
    TurbulentStrength_Urms (idx)= sqrt(TurbulentFluctuationSquare_Mean(idx))        
    
    Turbulent_Intensity(idx) = TurbulentStrength_Urms(idx)*(sqrt(TurbulentFluctuationArray_Mean(idx)));
    

Simply add (idx) to indicate that at the iteration 1 you are writing the result at the first element of the matrix, iteration 2 results is written at the position 2 etc. This way you will have a vector/matrix (depending on your initial dimensions) with data saved at each iteration of your "for2 cycle.

[muhammad choudhry]

that's the error I am getting now.

Unable to perform assignment because the indices on the left side are not compatible with the size of the right side.

Error in Turbulent_Intensity_line (line 17)

TurbulentFluctuation_Square(idx) = (TurbulentFluctuation_array).^2;

Answer 1

[KSSV]

P = 'F:\3-PIV_Experimental_Data\Calculations_TurbulentIntensity\line_Data\Elliptical_Side\Length\DesignPoint\110_outlet';
Q = 'F:\3-PIV_Experimental_Data\Calculations_TurbulentIntensity\line_Data\Elliptical_Side\Length\DesignPoint';
S = dir(fullfile(P,'*.csv'));
N = natsortfiles({S.name});
% Pre-allocate output vector
n = numel(N) ; 
TurbulentFluctuationArray_Mean = zeros(n,1) ; 
TurbulentFluctuationSquare_Mean = zeros(n,1) ; 
TurbulentStrength_Urms = zeros(n,1) ; 
Turbulent_Intensity = zeros(n,1) ; 

% loop over the file names
for idx = 1:n
    data = readtable( fullfile(P, N{idx}) ); % read the csv files
    
    TurbulentFluctuation_array = data.(13) ; 
    
    TurbulentFluctuationArray_Mean(idx) = mean(TurbulentFluctuation_array); %calculate the mean of each array from each folder        
    
      
    TurbulentFluctuation_Square = TurbulentFluctuation_array.^2;     % taking the square of the array of each array from each folder
    TurbulentFluctuationSquare_Mean(idx) = mean(TurbulentFluctuation_Square); %taking the mean of the sqaure value
    TurbulentStrength_Urms(idx) = sqrt(TurbulentFluctuationSquare_Mean(idx)) ;       % sqrt of the mean value
    Turbulent_Intensity(idx) = TurbulentStrength_Urms(idx)*(sqrt(TurbulentFluctuationArray_Mean(idx))); % calculating turbulent intensity 
end   
T = table(TurbulentFluctuationSquare_Mean,TurbulentStrength_Urms,Turbulent_Intensity) ; 
writetable(fullfile(Q, 'output.csv'), T); % its only saving first term value TurbulentFluctuationSquare_Mean

[muhammad choudhry]

Hi, I am getting the error below.

Error using *

Incorrect dimensions for matrix multiplication. Check that the number of columns in the first matrix matches the number of rows in the second matrix. To

perform elementwise multiplication, use '.*'.

Error in Turbulent_Intensity_line (line 25)

Turbulent_Intensity(idx) = TurbulentStrength_Urms*(sqrt(TurbulentFluctuationArray_Mean)); % calculating turbulent intensity

[KSSV]

Edited the code. Don't use numel(N,1). This will give result as 1 and your loop runs only once.

[muhammad choudhry]

perfect, thanks alot it worked! last problem. I want to save each field I ran column by column so I can further process them. Line below is not saving the data as I would like to save.

csvwrite(fullfile(Q, 'output.csv'), TurbulentFluctuationSquare_Mean, TurbulentFluctuation_Square, TurbulentFluctuationSquare_Mean, TurbulentStrength_Urms, Turbulent_Intensity)

[KSSV]

Edited the code.

[muhammad choudhry]

Error using writetable (line 179)

Incorrect argument order. writetable expects a table as its first argument and a filename as its second argument.

Error in Turbulent_Intensity_line (line 27)

writetable(fullfile(Q, 'results.csv'), T); % its only saving first term value TurbulentFluctuationSquare_Mean

[KSSV]

writetable(T,fullfile(Q, 'output.csv'));