Mike on the MATLAB Desktop

May 25th, 2009

There have been a number of requests recently asking that we support colorized output in the Command Window (here, here and here). I won’t be offering a way to colorize the Command Window content, but I will be offering an alternative way to generate colorized output for viewing in a web browser.

Some of the users I’ve talked with want to color their output in the Command Window so that they can easily pick out print-outs that indicate a problem. Imagine you had a long running program that printed various “good” diagnostics, but also occasionally printed out a message indicating that something wasn’t quite right and needed to be looked at. It would be nice to color that text in red, or some other attention grabbing color. This is the case we’ll address below.

We’ll start by writing a simple function that takes a string and wraps it in an HTML font tag. This function will also take a color, which will be used for the font tags color attribute. Because the result will be HTML , the color value can be anything supported by font‘s color attribute (e.g. red, #cccccc etc.). Here’s what that function looks like:

function colorizedstring = colorizestring(color, stringtocolorize)
%colorizestring wraps the given string in html that colors that text.
    colorizedstring = ['<font color="', color, '">', stringtocolorize, '</font>'];
end

Now all we need to do is use the function. Start by creating an HTML file in which to put your output text. Then, run your function and write to the output file as necessary using the colorizestring function. Finally, close the file for writing and open it using the web command.

Here’s what a sample usage might look like:

%% Open an HTML file to write the output into.
filename = 'colorizedoutput.html';
fid = fopen(filename, 'wt');

%% Do the long running calculation that generates lots of output.
for i=1:100
    outputswitch = rand;
    if rand < 0.80
    fprintf(fid, colorizestring('black', 'Everything is fine.<br/>'));
    elseif rand < 0.90
        fprintf(fid, colorizestring('orange', 'There may be a problem.<br/>'));
    else
        fprintf(fid, colorizestring('red', 'There is a problem.<br/>'));
    end

    fprintf(fid, 'some string<br/>');
end

%% Close the HTML output file.
fclose(fid);

%% Open the HTML output file in MATLAB's web browser.
web(filename);

and the resulting output:

This won’t solve everyone’s problems, but it should help to fill the gap until we can fully support colorized output in the Command Window.

17:06 UTC | Posted in Command Window, Editor | Permalink | 5 Comments »

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5 Responses to “Colorizing text output”

1. Timo replied on May 25th, 2009 at 17:56 UTC :
   

   What about CPRINTF by Yair Altman?
   It can be found in the File Exchange: http://www.mathworks.com/matlabcentral/fileexchange/24093

   This has been the File Exchange Pick of the Week on May 15th, but that blog article seems to have been removed now… Perhaps because CPRINTF uses undocumented features?

2. Petter replied on May 26th, 2009 at 06:28 UTC :
   

   Yeah, CPRINTF works beautifully.

3. Scott Hirsch replied on May 26th, 2009 at 11:54 UTC :
   

   For those who find CPRINTF addresses their needs well – keep in mind Yair’s warning that code relying on undocumented/unsupported functionality may be more likely to break. If you want your code to last, code defensively:

   try
     cprintf(...
   catch ME
     fprintf(...
   end
   

4. Chuck Andraka replied on July 21st, 2010 at 17:47 UTC :
   

   Mike:

   Your approach writes this to file. Is there any way to dynamically and continuously write this to a browser that is open? This would “simulate” the output (command) window more closely.

   Thanks
   Chuck

5. Mike replied on July 22nd, 2010 at 13:07 UTC :
   

   @Chuck,
   Not in an easy and documented way. The best thing I can think of is to put in some javascript that reloads the page every so often.

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