Save a double array to a text file

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AP
AP on 3 Apr 2021
Edited: Image Analyst on 4 Apr 2021
Hello,
I have a double array that looks like this:
0.3764 0.6801 0.1926 -0.1987 0.3531
0.0313 -0.2461 0.0218 0.0299 -0.3008
-0.1811 -0.1639 -0.0698 0.0397 -0.2341
0.3469 0.3152 6.1030 -0.3613 0.3749
-0.5791 -0.2253 -0.3613 6.1030 -0.2178
I want to save this to a text file so that the output text file looks exactly like the above data
I tried the dlmwrite command but I do not want to specify precision, and the examples I have found create a file with ' ; ' in between which is not something I want.

Accepted Answer

Image Analyst
Image Analyst on 3 Apr 2021
Edited: Image Analyst on 4 Apr 2021
Try this:
clc; % Clear the command window.
close all; % Close all figures (except those of imtool.)
clear; % Erase all existing variables. Or clearvars if you want.
workspace; % Make sure the workspace panel is showing.
format short g;
format compact;
fontSize = 18;
fprintf('Beginning to run %s.m ...\n', mfilename);
fileName = 'deleteme.txt';
fid = fopen(fileName, 'wt');
m = [
0.3764 0.6801 0.1926 -0.1987 0.3531
0.0313 -0.2461 0.0218 0.0299 -0.3008
-0.1811 -0.1639 -0.0698 0.0397 -0.2341
0.3469 0.3152 6.1030 -0.3613 0.3749
-0.5791 -0.2253 -0.3613 6.1030 -0.2178
]
[rows, columns] = size(m);
for row = 1 : rows
for col = 1 : columns
fprintf(fid, '%f ', m(row, col));
end
fprintf(fid, '\n');
end
fclose(fid);
winopen(fileName); % Open in Notepad or Wordpad
  1 Comment
AP
AP on 3 Apr 2021
Great! This worked the way I wanted.Thank you!

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More Answers (2)

the cyclist
the cyclist on 3 Apr 2021
Regardless of what is displayed to the MATLAB command window (in your case, the default format, it seems), an array of type double is storing 64-bit, double-precision floating-point values.
So, I don't believe it is possible for you to achieve both of the following things you want:
  • write that exact format
  • do not specify the precision (i.e. format)
Also, all functions that write output have to choose some delimiter by default. Usually, that delimiter can be chosen to be something else.
The writematrix command might do what you want?

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