how to read complex file data to matrix

Question

vincent lin 2020-1-17

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/500691-how-to-read-complex-file-data-to-matrix

编辑： per isakson 2020-1-18

a.txt

I have a.txt file, with complex data. the format is

958138021e-02	0.64646110658609712285 + 0.093290941560866688653j	
958139648e-02	0.32117256288141476928 - 0.061542254916540022058j	
958141276e-02	-0.22359569118086644601 + 0.3585713533321416846j	
958142904e-02	-0.22397218216792619261 + 0.082213621398327246803j	
999960938e-02	0	
999962565e-02	0	
999964193e-02	0	
999965820e-02	0
000000000e-02	0.10412797744247889731 + 0.0081123700776114041067j		

There's space between + and -. how can I read this file into a matrix with seperated I part and Q part.

like

958138021e-02  0.64646110658609712285   0.093290941560866688653
...
999960938e-02	0                       0
000000000e-02	0.10412797744247889731  0.0081123700776114041067

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stozaki 2020-1-17

Could you attach a real text file?

vincent lin 2020-1-17

yes. a.txt added

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Answer 1

per isakson 2020-1-17

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https://ww2.mathworks.cn/matlabcentral/answers/500691-how-to-read-complex-file-data-to-matrix#answer_410549

Following Walter's advise

%%
chr = fileread('a.txt');
%%
chr = strrep( chr, ' + ', '+' );
chr = strrep( chr, ' - ', '-' );
cac = textscan( chr, '%f%f' );
%%
M = cat( 2, cac{1}, real(cac{2}), imag(cac{2}) );
>> M(1:3,:)
ans =
            0      0.10413    0.0081124
   1.6276e-08     -0.04608    -0.073765
   3.2552e-08    -0.038321     0.076231

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vincent lin 2020-1-17

编辑：per isakson 2020-1-18

thank you. This works and is fast. I find there's another code by reading line by line. It works but is very slow. Your method is faster

fid = fopen ('a.txt','r'); 
ii  = 1;
while ~feof(fid)
    acorrente(ii, :) = str2num(fgets(fid));
    ii = ii + 1;
end
fclose(fid);
data = [real(acorrente(:,1)) real(acorrente(:,2)) imag(acorrente(:,2))];

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Answer 2

Walter Roberson 2020-1-17

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Sometimes easiest is to read the file as a character vector, use regexp to remove the space around the sign of the imaginary part, and then textscan. textscan and other numeric formats can read complex values when there is no space.

Or read the file as string and regexp to change lines that do not end in j to append + 0j on them. With all lines having the same format you can easily textscan to extract real and imaginary separately.