import complex column into matlab

Hi everybody,

I have a two-column data that I want to import into the workplace. The two columns are separated by comma, for all real numbers I could use the following code,

data = textread('data.txt', '', 'delimiter', ',');
x = data(1:(length(data(:,1))-1),1);     
y = data(1:(length(data(:,2))-1),2);

But now I have data after FFT like this, where the second column is complex,

0,-7.45678527326516E-7
0.0123532704572966,-9.13085574558244E-7 - 3.24050470823079E-7i
0.0247065409145915,-1.78617729703184E-6 + 9.66937131199859E-7i
0.0370598113718881,3.11409269891353E-6 - 1.40731487179325E-5i
0.0494130818291847,-8.23979324344331E-6 + 4.94108233557163E-5i
0.0617663522864795,3.95217467868805E-5 - 1.00035273201451E-4i
0.0741196227437761,-4.26665707593228E-5 + 7.19117803282971E-5i

How can I import it? The file can be saved as .txt, .csv, or .dat.

Thanks a lot!!

[dpb]

Can you modify the process that writes the file any at all? If you would at least

a) Include the explicit zero imaginary part of the first row, and

b) eliminate the space between the sign and the numeric value for the imaginary component

it would be simpler to parse with standard formatting descriptors.

Answer 1

[per isakson]

AFAIK: The complex number in the file need to be written without spaces between the real and the imaginary parts. However, I failed to find that stated in the documentation.

One way to read your file is to

• read the entire file to one character string
• remove the spaces
• parse the string with the function, textscan

Try

    >> cac = cssm()
    cac = 
        [7x1 double]    [7x1 double]
    >> cac{1}
    ans =
             0
        0.0124
        0.0247
        0.0371
        0.0494
        0.0618
        0.0741
    >> cac{2}
    ans =
       1.0e-03 *
      -0.0007 + 0.0000i
      -0.0009 - 0.0003i
      -0.0018 + 0.0010i
       0.0031 - 0.0141i
      -0.0082 + 0.0494i
       0.0395 - 0.1000i
      -0.0427 + 0.0719i
    >>

where

    function    cac = cssm()
        str = fileread( 'cssm.txt' );
        str = strrep( str, ' ', '' );
        cac = textscan( str, '%f%f', 'Delimiter', ',' ); 
    end

and where cssm.txt contains

    0,-7.45678527326516E-7
    0.0123532704572966,-9.13085574558244E-7 - 3.24050470823079E-7i
    0.0247065409145915,-1.78617729703184E-6 + 9.66937131199859E-7i
    0.0370598113718881,3.11409269891353E-6 - 1.40731487179325E-5i
    0.0494130818291847,-8.23979324344331E-6 + 4.94108233557163E-5i
    0.0617663522864795,3.95217467868805E-5 - 1.00035273201451E-4i
    0.0741196227437761,-4.26665707593228E-5 + 7.19117803282971E-5i

&nbsp

Or use CollectOutput and read to one matrix

    >> cac = cssm()
    cac = 
        [7x2 double]
    >> cac{1}
    ans =
       0.0000 + 0.0000i  -0.0000 + 0.0000i
       0.0124 + 0.0000i  -0.0000 - 0.0000i
       0.0247 + 0.0000i  -0.0000 + 0.0000i
       0.0371 + 0.0000i   0.0000 - 0.0000i
       0.0494 + 0.0000i  -0.0000 + 0.0000i
       0.0618 + 0.0000i   0.0000 - 0.0001i
       0.0741 + 0.0000i  -0.0000 + 0.0001i

where

    function    cac = cssm()
        str = fileread( 'cssm.txt' );
        str = strrep( str, ' ', '' );
        cac = textscan( str, '%f%f', 'Delimiter',',', 'CollectOutput',true ); 
    end

Answer 2

[Matthew Parry]

In R2019a or later you can use

data = readmatrix(fname);