Replace comma with dot after fopen

2021 10 19
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更新时间：2021 10 20
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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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KSSV
KSSV 2021-10-19
Read about strrep.
Stephen23
Stephen23 2021-10-19
"I have searched between the answers in the Matlab Central but I have found nothing"
Here are 339 results, many of which are related to file importing:
https://www.mathworks.com/matlabcentral/answers/?term=decimal+comma
Daniele Sonaglioni
Daniele Sonaglioni 2021-10-19
@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
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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 采纳的回答

Star Strider
Star Strider 2021-10-19

0 个投票

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
Daniele Sonaglioni 2021-10-19
Your idea is quite good but using readmatrix will result in a great change in the code and this is something I want to avoid. I have attached the code in my previous answer, maybe you remeber it: can you suggest something about that code?
Star Strider
Star Strider 2021-10-19
I don’t remember it, however that looks like my code.
One possibility would be to read the variables in a strings rather than numeric, then use strrep on the strings, and then read the entire line using textscan.
Another option would be to read the entire file as text using the fileread funciton, then do the conversion and use textscan, since it can take character vectors as input.
Attaching the file would help.
.
Daniele Sonaglioni
Daniele Sonaglioni 2021-10-20
This the kind of file I want to convert.
Star Strider
Star Strider 2021-10-20
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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更多回答（1 个）

Stephen23
Stephen23 2021-10-20
编辑：Stephen23 2021-10-20
Ran in:

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Ran in:
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
Index t Ts Value _____ _____ _______ _________ 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 5 0.005 -19.36 -0.17076 6 0.006 -19.262 -0.19742 7 0.007 -19.161 -0.21605 8 0.008 -19.061 -0.22971 9 0.009 -18.96 -0.24071 10 0.01 -18.861 -0.24984 11 0.011 -18.76 -0.25674 12 0.012 -18.661 -0.26249 13 0.013 -18.56 -0.26758 14 0.014 -18.461 -0.27248 15 0.015 -18.36 -0.27657

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