[Octave-bug-tracker] [bug #32720] ML compatibility of textread.m and strread.m

[Philip Nienhuis]

URL:
  <http://savannah.gnu.org/bugs/?32720>

                 Summary: ML compatibility of textread.m and strread.m
                 Project: GNU Octave
            Submitted by: philipnienhuis
            Submitted on: Tue 08 Mar 2011 08:46:51 PM GMT
                Category: None
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Incorrect Result
                  Status: None
             Assigned to: None
         Originator Name: Philip Nienhuis
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
                 Release: dev
        Operating System: Microsoft Windows

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Details:

I've hit a few incompatibilities betweem Matlab's and Octave's textread.m and
strread.m (the two are strongly interlinked in Octave 3.4.x)

1. As per the on-line ML docs, textread's default for whitespace = ' \t\b' 
(note the leading space).
Octave's textread as it stands doesn't have a default whitespace setting at
all. Instead it simply conveys all given optional param/value pairs as
varargin{:} to strread.m and so defaults to strread's default whitespace which
is ' \n\r\t\b'  (again, note leading space).
==> This is easy to fix by checking for a default 'whitespace' argument
setting in textread and -if needed- adapting varargin.
See attached patch # 1 (diff -cp with mercurial as of 2011-03-08_21:30)

2. As per the ML docs, textread offers an option of preserving leading and
trailing spaces by calling it like:
     textread('myfile.txt', '%s', 'whitespace', '')
When I do this in Octave 3.4.0, leading whitespace is consequently trimmed.
Following the internal logic I find that textread.m calls strread.m, which
calls an internal subfunction split_by(), which always calls strtrim() (in
line 246 of strread.m).
The easiest fix is simply commenting out or deleting the call to strtrim(). 

3. strread.m accepts a 'whitespace' argument but doesn't do anything with it,
except substituting it into 'delimiter' arg if that is not supplied. 

4. No checks for empty 'delimiter' or 'whitespace', or overlap in these params
are performed.

I've added a few checks, and implemented a -perhaps rough- trick to remove
repeated whitespace. Also, in case of a non-empty 'whitespace' setting,
strtrim() is called.
==> see patch # 2 (diff -cp with mercurial as of 2011-03-08_21:30)

All tests (of strread) pass and AFAICS ML and Octave behavior is now
identical.

I've also added a changelog entry (attachment #3).
Sorry I have no development setup at hand now (I made these fixes using ML at
work and octave-3.3.91_MinGW by Tatsuro) so I can't make changesets - I don't
even know how to make them.




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File Attachments:


-------------------------------------------------------
Date: Tue 08 Mar 2011 08:46:51 PM GMT  Name: textread.m.diff  Size: 639B   By:
philipnienhuis

<http://savannah.gnu.org/bugs/download.php?file_id=22859>
-------------------------------------------------------
Date: Tue 08 Mar 2011 08:46:51 PM GMT  Name: strread.m.diff  Size: 4kB   By:
philipnienhuis

<http://savannah.gnu.org/bugs/download.php?file_id=22860>
-------------------------------------------------------
Date: Tue 08 Mar 2011 08:46:51 PM GMT  Name: Changelog  Size: 287B   By:
philipnienhuis

<http://savannah.gnu.org/bugs/download.php?file_id=22861>

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