Replace comma with dot after fopen

Question

Daniele Sonaglioni 2021-10-19

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1566908-replace-comma-with-dot-after-fopen

评论： Star Strider 2021-10-20

Hello everyone,

I am having some problems with Matlab.

I import a txt file with fopen and, after imported, I want to convert the commas in the file with dots but I do not know how to do. I have searched between the answers in the Matlab Central but I have found nothing.

Thank you for the help.

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Daniele Sonaglioni 2021-10-19

在 MATLAB Online 中打开

@KSSV Thanks but it does not help me because it must be used before fopen (as far as I have seen).

I attach a part of my code to let you know what I am working on:

fidi = fopen('myfile.txt','rt');
k1 = 1;
while ~feof(fidi)
    readline = fgetl(fidi);
    
    if strcmp(readline,'Results:')
        C = textscan(fidi, '%f%f%f%f %*f%*f%*f%*f%*f%*f', 'HeaderLines',9, 'CollectOutput',1);
    else
        C = textscan(fidi, '%f%f%f%f %*f%*f%*f%*f%*f%*f', 'HeaderLines',0, 'CollectOutput',1);
    end
    M = cell2mat(C);
    fprintf(1,'\tSection %2d: (%4d x %d)\n', k1, size(M));
    if isempty(M)                                           % Empty Matrix Indicates End-Of-File
        fprintf(1,'Reading finished, %d Sections\n',k1-1);
        break
    end
    D{k1,:} = M;
    fseek(fidi, 0, 0);
    k1 = k1 + 1;
end
fclose(fidi);

Daniele Sonaglioni 2021-10-19

@Stephen I am aware that there are results on the Matlab Central (I have also checked them) but I have not found anything useful.

I know that before asking question one has to check on the central.

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Answer 1

Star Strider 2021-10-19

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1566908-replace-comma-with-dot-after-fopen#answer_811773

For MATLAB versions R2019a and later, the readmatrix function permits definition of the 'DecimalSeparator' (see the Text Files Only documentation section, since ther is no direct link to it) as a name-value pair argument.

.

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Daniele Sonaglioni 2021-10-20

trial_file.txt

This the kind of file I want to convert.

Star Strider 2021-10-20

在 MATLAB Online 中打开

Since you stated that using readmatrix (or readtable) would disrupt your existing code, an alternative would be textscan.

The online Run feature would not let me do all this here, so I did it offline —

fidi = fopen('trial_file.txt','rt');
C = textscan(fidi, '%f%s%s%s', 'HeaderLines',10, 'CollectOutput',1, 'EndOfLine','\r\n');
fclose(fidi);
M = [C{1} str2double(strrep(C{2},',','.'))];
Check = M(1:5,:)
Check =
            0            0      -19.773    -0.009783
            1        0.001      -19.733    -0.015429
            2        0.002      -19.655    -0.038148
            3        0.003      -19.564    -0.081012
            4        0.004      -19.462     -0.13152

That imports the file and coinverts it correctly so it can be used in computations.

.

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Answer 2

Stephen23 2021-10-20

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1566908-replace-comma-with-dot-after-fopen#answer_812473

编辑：Stephen23 2021-10-20

在 MATLAB Online 中打开

trial_file.txt

fnm = 'trial_file.txt';
opt = detectImportOptions(fnm, 'VariableNamesLine',9, 'VariableUnitsLine',10, 'DecimalSeparator',',', 'ExtraColumnsRule','ignore');
opt.DataLines = [11,Inf];
tbl = readtable(fnm, opt)
tbl = 69227×4 table
IndextTsValue__________________________

        0    -19.773    -0.009783
    0.001    -19.733    -0.015429
    0.002    -19.655    -0.038148
    0.003    -19.564    -0.081012
    0.004    -19.462     -0.13152
    0.005     -19.36     -0.17076
    0.006    -19.262     -0.19742
    0.007    -19.161     -0.21605
    0.008    -19.061     -0.22971
    0.009     -18.96     -0.24071
     0.01    -18.861     -0.24984
    0.011     -18.76     -0.25674
    0.012    -18.661     -0.26249
    0.013     -18.56     -0.26758
    0.014    -18.461     -0.27248
    0.015     -18.36     -0.27657