How to solve this errror about reading in complex numbers?

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riki singh
riki singh 2022-10-9
编辑： dpb 2022-10-9
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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回答（2 个）

dpb
dpb 2022-10-9
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".
  2 个评论
riki singh
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
dpb 2022-10-9
编辑：dpb 2022-10-9
Ran in:
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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Image Analyst
Image Analyst 2022-10-9
Ran in:
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

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