How do I overwrite text in the command window?
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Kyle Poe
on 10 Jul 2017
Answered: Cristi Savlovschi
on 15 Jul 2021
I am trying to write a counter that uses the format "processing subject ### of 123", where the ### changes in the command window upon every subject change. I know this could be accomplished in a loop with something like
fprintf('processing subject 000 of 123')
for number in 1:123
fprintf('\b\b\b\b\b\b\b\b\b\b%s of 123',subnum(number))
% subnum is a 3-digit number in character form to preserve the 3-digit format declared elsewhere
end
But that is ugly and terribly inefficient. How do I rectify the problem?
0 Comments
Accepted Answer
Walter Roberson
on 10 Jul 2017
That is the most efficient way. There is no way to address individual characters or pixels of the command output window (unless perhaps you can get at it from the java level.)
2 Comments
dpb
on 10 Jul 2017
And, \r is interpreted same as \n so that doesn't help, either.
But, might consider either a waitbar or just a msgbox
More Answers (4)
Eeshan Bhatt
on 25 Oct 2018
Edited: Eeshan Bhatt
on 25 Oct 2018
I know you have an accepted answer, but here's a quick robust code that I use often.
nbytes = fprintf('processing 0 of %d', length(z));
for nz = z
while nbytes > 0
fprintf('\b')
nbytes = nbytes - 1;
end
nbytes = fprintf('processing %d of %d', nz, length(z));
% YOUR PROCESS HERE
%
%
%
end
1 Comment
Ted Shultz
on 19 Jul 2019
Edited: Ted Shultz
on 19 Jul 2019
Eeshan, this is a nice solution! I would propose this small modification so that it runs a little faster, and is a little simpler:
nbytes = fprintf('processing 0 of %d', length(z));
for nz = z
fprintf(repmat('\b',1,nbytes))
nbytes = fprintf('processing %d of %d\n', nz, length(z));
% YOUR PROCESS HERE
%
%
%
end
Boubat Matthieu
on 28 Jul 2020
I packaged the use of fprintf('\b') into a class hoping that it will ease the way to rewrite/update text in the command window. If you want to give it a try it's available here.
It goes like this:
prefix = 'processing subject ';
suffix = ' of 123';
progression = UpdatableText(prefix,suffix); % UpdatableText is the actual class
for i = 1:123
progression.print(num2str(i));
end
There are also methods to easily add a percent value and a progress bar.
0 Comments
Cristi Savlovschi
on 15 Jul 2021
function dispProgressMsg(msg)
ASCII_BKSP_CHAR = 8;
persistent prevMsgLen;
if isempty(prevMsgLen)
prevMsgLen = 0;
end
disp([ char(repmat(ASCII_BKSP_CHAR,1,prevMsgLen)) msg]);
prevMsgLen = numel(msg)+1;
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