Read row x to row y in a textfile

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Marthe Fenne Vestly 2017-10-27

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https://ww2.mathworks.cn/matlabcentral/answers/363639-read-row-x-to-row-y-in-a-textfile

评论： Cedric 2017-11-2

采纳的回答： Cedric

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Hi,

I have a very long textfile that I want to read the lines from 32781 to 32894, excluding the lines above and below, and store the lines in a new text files. I have made this code, but it does not work.

The txt-file have some lines with two columns and other with three and four. The lines I am interested in only have two columns.

[T1,PSA1]=textread('FFC_M7_1.txt', '%f %f','headerlines',32781);
[T,PSA] = [T1(32782:32894), PSA1(32782:32894)]
f1=fopen('FFC_M7_1_test.txt','w');
for i= 1:length(T)
fprintf(f1,'%11.4f %11.4f\n',[T(i) PSA(i)]);
end
fclose(f1);

This message appear when I try to run the code:

Error using dataread
Trouble reading floating point number from file (row 114, field 1) ==> Frequency (Hz)              A
Error in textread (line 174)
[varargout{1:nlhs}]=dataread('file',varargin{:}); %#ok<REMFF1>
Error in WritePSA (line 1)
[T1,PSA1]=textread('FFC_M7_1.txt', '%f %f','headerlines',32781);

Does anyone know how to do this?

Thanks, Marthe

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采纳的回答

Cedric 2017-10-27

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/363639-read-row-x-to-row-y-in-a-textfile#answer_288124

编辑：Cedric 2017-10-27

在 MATLAB Online 中打开

Is the following working?

[T1,PSA1]=textread('FFC_M7_1.txt', '%f %f %*s %*s','headerlines',32781);

 content    = fileread( 'FFC_M7_1_test.txt' ) ;
 lineStarts = [0, strfind( content, sprintf('\n') )] + 1 ;
 block      = content(lineStarts(32782) : (lineStarts(32895)-1)) ;
 data       = reshape( str2double( regexp( block, '[\d\.\-]+', 'match' )), 2, [] ).' ;

I cannot test right now though.