From help-request at octave dot org Tue Jun  8 11:43:29 2004
Subject: Re: Plotting data from a file containing comments as first lines
From: Jonathan Stickel <jjstickel at sbcglobal dot net>
To: help at octave dot org
Date: Tue, 08 Jun 2004 09:17:51 -0700

vincent dot marembert at free dot fr wrote:
> Hi, 
>  
> my problem: 
> I would like to plot the data contained in a file beginning with comments... 
> The file looks like: 
>  
> blabla1 
> blabla2 
> dsfsdsdfd 
> 1       3 
> -5      6 
> 0       8 
> 1       8 
>  
> Of course it would be easy if there was no comments at the beginning, I 
> would just load the data typing  
> load data 
> and then plot it with 
> plot data 
>  
> Is there a way to tell Matlab (or Octave, because I work a lot with Octave) 
> to ignore the first 3 or 4 lines ? There must be one, but I can t find 
> it... 
>  

For this, I think you must use the low-level fopen, fscanf type 
commands.  Pasted below is a function I just wrote that I think will 
satisfy your needs.

Jonathan


function data=datareadwh(filename,nhl,nc)
   %%data=datareadwh(filename,nhl,nc)
   %%  Read data from a file, skipping the first nhl lines
   %%  (header lines).  nc is the number of columns the data
   %%  is expected to be in.

   %%  author:  Jonathan Stickel
   %%  created:  8 June 2004
   %%  modified:  8 June 2004


   [fid,msg] = fopen (filename, "r");

   for i=1:nhl
     fgetl(fid);
   endfor

   [data,count] = fscanf (fid, "%f");
   fclose(fid);

   nr=count/nc;
   if ( nr-floor(nr) )
     disp("warning:  data read is not an integer multiple of the 
specified number of columns;")
     disp("returning data in a single column")
   else
     data=reshape (data,nc,nr)';
   endif

endfunction



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