add column to file with dlmwrite

Hello, is there anyway to add a column to an existing file using dlmwrite?

I've tried to transpose it to add lines instead and later convert it to columns again but I get the error " FILENAME must be a character vector "

A = [0.23;0.44;0.65;0.12];
A = A';
oldfile = dlmread('testfile1.txt');
oldfile = oldfile';
dlmwrite(oldfile,A,'-append','newline','pc','delimiter',' ')

[Star Strider]

Reference: Write column in .txt file

Answer 1

[Walter Roberson]

Only by rewriting the entire file.

[Marisabel Gonzalez]

Hi Walter, would you mind showing a code to do that?

[Walter Roberson]

oldfile = dlmread('testfile1.txt');
A = [0.23; 0.44; 0.65; 0.12];
oldfile(1:length(A), end+1) = A;   %done this way in case the rows are not the same
dlmwrite('testfile1.txt', oldfile, 'newline', 'pc', 'delimeter', ' ');

[Devikrishna]

My matrix is in the form 39×39 I want to add a column using dlmwrite and make 39× 40

[Walter Roberson]

The way that text files are designed in Windows, Mac, and Linux makes it impossible to add additional information to a row without rewriting the entire file. That applies not just to dlmwrite but also to writematrix and to using excel.

You need to use a system like I posted the code for, of reading the existing file, adding the new column in memory, and writing out the revised content