How to solve this errror about reading in complex numbers?

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.

Answer 1

[dpb]

Previously answered what appears to be virtually identical Q?

<answers/1818965-how-to-read-only-last-2-columns-of-csv-format-file>

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

[riki singh]

i m getting an error in

data1=cell2mat(data) where after converting to matrix

i am nt able to extract last 2 columns

[dpb]

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!"

Answer 2

[Image Analyst]

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