How to solve this errror about reading in complex numbers?

Question

riki singh 2022-10-9

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1820550-how-to-solve-this-errror-about-reading-in-complex-numbers

编辑： dpb 2022-10-9

plot.csv

filename='plot.csv';
fid=fopen(filename,'r');
data=textscan(fid,'%f %f %f %f %f','Delimiter','Whitespace','HeaderLines',5);
fclose(fid);
data1=cell2mat(data);
real=data1(:,4);
img=data1(:,5);
complex=real+1i*img

after reading the data from .csv format, I want only 4th and 5th column only ... only the last 2 columns.

Then get into a complex number = real+1i*img with format(a+bi), but I am getting an error.

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Answer 1

dpb 2022-10-9

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https://ww2.mathworks.cn/matlabcentral/answers/1820550-how-to-solve-this-errror-about-reading-in-complex-numbers#answer_1069855

Previously answered what appears to be virtually identical Q?

The short answer is "read the whole file and save just what need in memory".

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riki singh 2022-10-9

i m getting an error in

data1=cell2mat(data) where after converting to matrix

i am nt able to extract last 2 columns

dpb 2022-10-9

编辑：dpb 2022-10-9

在 MATLAB Online 中打开

Well, works just fine for me...

filename=websave('plot.csv','https://www.mathworks.com/matlabcentral/answers/uploaded_files/1150415/plot.csv');
fid=fopen(filename,'r');
data=cell2mat(textscan(fid,'','Delimiter',',','HeaderLines',1));
fclose(fid);
Y=complex(data(:,4),data(:,5))
Y = 
  -4.2000 - 5.2000i
  -3.2000 + 6.2000i
  -5.2000 + 3.2000i
  -3.2000 - 5.2000i
  -6.2000 - 6.3000i
  -2.3000 - 9.2000i
   2.3000 - 6.2000i
   2.3000 - 3.2000i
   6.2000 - 6.3000i
   3.2000 - 7.8000i

Don't alias builtin complex function; "there be dragons!"

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Answer 2

Image Analyst 2022-10-9

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链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1820550-how-to-solve-this-errror-about-reading-in-complex-numbers#answer_1069875

在 MATLAB Online 中打开

plot.csv

Try readtable:

filename='plot.csv';
data= readtable(filename)
data = 10×5 table
    a1    a2    b1     b2      C1 
    __    __    __    ____    ____

     1    0     1     -4.2    -5.2
     2    0     2     -3.2     6.2
     3    0     3     -5.2     3.2
     4    0     4     -3.2    -5.2
     5    0     5     -6.2    -6.3
     6    0     1     -2.3    -9.2
     7    0     2      2.3    -6.2
     8    0     3      2.3    -3.2
     9    0     4      6.2    -6.3
    10    0     5      3.2    -7.8
% Get real component from column 4.
realValues = data{:,4}
realValues = 10×1
   -4.2000
   -3.2000
   -5.2000
   -3.2000
   -6.2000
   -2.3000
    2.3000
    2.3000
    6.2000
    3.2000
% Get imaginary component from column 5.
imaginaryValues = data{:,5}
imaginaryValues = 10×1
   -5.2000
    6.2000
    3.2000
   -5.2000
   -6.3000
   -9.2000
   -6.2000
   -3.2000
   -6.3000
   -7.8000
complexValues = realValues + 1i * imaginaryValues
complexValues = 
  -4.2000 - 5.2000i
  -3.2000 + 6.2000i
  -5.2000 + 3.2000i
  -3.2000 - 5.2000i
  -6.2000 - 6.3000i
  -2.3000 - 9.2000i
   2.3000 - 6.2000i
   2.3000 - 3.2000i
   6.2000 - 6.3000i
   3.2000 - 7.8000i