How to read CSV file and save the result to another CSV file

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Kong 2020-3-26

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/513108-how-to-read-csv-file-and-save-the-result-to-another-csv-file

编辑： Peng Li 2020-3-26

采纳的回答： Peng Li

在 MATLAB Online 中打开

Hello.

I have several CSV files.

After processing each CSV file, I want to save each CSV file to other name using for loop.

The names of input file are different (bend1.csv, walk2.csv, jogging2.csv, ....)

clear all
close all
X = csvread('bend1.csv');
X = X(:,1:28);
data = X';
% After processing......
% I want to each Y matrix to CSV files
Y = Phi_NuMax * X';
csvwrite('/result/bend1.csv', Y);

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Akira Agata 2020-3-26

编辑：Akira Agata 2020-3-26

You mean, you have many CSV files in one folder and want to save in another folder with the same file name after applying some processing?

Kong 2020-3-26

YES! I want to do it.

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Answer 1

Peng Li 2020-3-26

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/513108-how-to-read-csv-file-and-save-the-result-to-another-csv-file#answer_422130

在 MATLAB Online 中打开

a simple structure:

outDir = yourDestination.
allCsvFiles = dir(fullfile(yourDirectory, '.*csv'));
for iA = 1:length(allCsvFiles)
    curFile = allCsvFiles(iA).name;
    
    yourTable = readtable(fullfile(yourDirectory, curFile));
    % your process
    
    writetable(fullfile(outDir, curFile), yourTable);
end

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Kong 2020-3-26

在 MATLAB Online 中打开

Thank you so much.

I don't know what is curFile.

Could you check my code?

clear all
close all
outDir = '/';
allCsvFiles = dir(fullfile('/', '.*csv'));
for iA = 1:length(allCsvFiles)
    curFile = allCsvFiles(iA).name;
    
    yourTable = readtable(fullfile('/', curFile));
    % your process
    curFile = curFile(:,1:28);
    data = curFile';
    
    opt.init_num_secants = 28;
    idx1 = random('unid',size(data, 2), opt.init_num_secants, 1);
    idx2 = random('unid',size(data, 2), opt.init_num_secants, 1);
    secants = data(:, idx1)-data(:, idx2);
    D1 = abs(secants);
    numSecants = size(X,2);
    options.landmarks = 1:28; 
    [geo] = IsomapII(D1, 'k', 3, options); 
    secants = geo/norm(geo,2);
    
    
    %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
    %%%%%Parameter setting
    %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
    opt.outer_iterations = 1000;
    
    switch 'l-bfgs'
        case 'grad'
            opt.linear_solver = 'grad';
            opt.tau = 1e-1; % gradient step size
            opt.inner_iterations = 10;
            opt.beta1 = 1e-1; opt.beta2 = 1e-1; %penalty parameters
            opt.eta1 = 1; opt.eta2 = 1; %lagrangian update
        case 'cgs'
            opt.linear_solver = 'cgs';
            opt.linear_iterations = 10;
            opt.inner_iterations = 1;
            opt.beta1 = 1; opt.beta2 = 1; %penalty parameters
            opt.eta1 = 1.618; opt.eta2 = 1.618; %lagrangian update
        case 'l-bfgs'
            opt.linear_solver = 'l-bfgs';
            opt.linear_iterations = 3;
            opt.lbfgs_rank = 5;
            opt.inner_iterations = 1;
            opt.beta1 = 1; opt.beta2 = 1; %penalty parameters
            opt.eta1 = 1.618; opt.eta2 = 1.618; %lagrangian update
    end
    %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
    %%End parameters
    %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
    delta = -3000; %max-margin parameter
    funA = @(z) funA_secants_WY(z, secants);
    funAT = @(z) funAT_secants_WY(z, secants);
    b = ones(numSecants, 1);
    ticID = tic;
    [P, L, q, Lambda, w] = NuMax(funA, funAT, b, delta, opt);
    toc(ticID);
    [U, S, V] = svd(P);
    r = rank(P);
    U1 = U(:, 1:r);
    U1 = (U1 - min(U1(:)))/(max(U1(:))-min(U1(:)));
    Phi_NuMax = (U(:, 1:r)*(S(1:r, 1:r).^(1/2)))';
    
    Y = Phi_NuMax * X';
    Y = Y';
    
    writetable(fullfile(outDir, curFile), yourTable);
end

Kong 2020-3-26

编辑：Kong 2020-3-26

I am sorry to bother you.

I changed outDir. When I tried to read each CSV file, what is Table?

yourTable is empty.

Peng Li 2020-3-26

编辑：Peng Li 2020-3-26

In the dir call, replace .*csv with *.csv.

Sorry it was my mistake that I had this typo in my example lol

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How to read CSV file and save the result to another CSV file

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