bugGNU Octave - Bugs: bug #54432, strmatch incompatibilities with...


bug #54432: strmatch incompatibilities with Matlab when using empty inputs

Submitted by:  Arnaud Delorme <arnodelorme>
Submitted on:  Thu 02 Aug 2018 04:22:28 PM UTC  
Category:  Octave Function Severity:  3 - Normal
Priority:  3 - Low Item Group:  Matlab Compatibility
Status:  Confirmed Assigned to:  None
Originator Name:  Open/Closed:  Open
Release:  4.4.0 Operating System:  Any

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( Jump to the original submission)

Wed 08 Aug 2018 06:44:36 PM UTC, comment #6: 

I checked in a small additional change to accept an empty cellstr here (https://hg.savannah.gnu.org/hgweb/octave/rev/e4f670d9df5c).

Rik <rik5>
Project Administrator
Fri 03 Aug 2018 06:14:00 PM UTC, comment #5: 

The other bit about an empty string always matching is just weird.  Trying to deduce the exact ruleset is tedious, and this function is strongly recommended not to be used by Matlab.  As such, there's not much incentive to work on it.

If someone wants to amend strmatch, they need to also take in to account results from bug #49601 which are equally bizarre.

>> strmatch(ones(1,1),ones(0,0))
ans =
>> strmatch(ones(0,0),ones(1,1))
ans =
>> strmatch(ones(0,1,0,0),ones(1,1))
ans =

Rik <rik5>
Project Administrator
Fri 03 Aug 2018 06:09:32 PM UTC, comment #4: 

I changed strmatch to accept a single cellstr as the first input in this cset (https://hg.savannah.gnu.org/hgweb/octave/rev/799dcddaf158).

Rik <rik5>
Project Administrator
Thu 02 Aug 2018 09:16:15 PM UTC, comment #3: 

My code has been functional on Matlab since 2000. So pretty much all versions since Matlab 5.3

>> strmatch ('', 'a')

ans =


>> strmatch ({'on'}, {'on', 'off'}, 'exact')

ans =


Arnaud Delorme <arnodelorme>
Thu 02 Aug 2018 08:40:25 PM UTC, comment #2: 

Can you use verbatim tags when posting code samples?  It seems that some of the examples may have been truncated.

I also wonder if this has changed.  I don't recall strmatch with a null input matching any character.  That is more of a regexp kind of behavior.  What does this return which doesn't use cell array of strings?

strmatch ('', 'a')

Also, can you try

strmatch ({'on'}, {'on', 'off'}, 'exact')

Rik <rik5>
Project Administrator
Thu 02 Aug 2018 04:39:19 PM UTC, comment #1: 

I have found another difference

Matlab 2018a
strmatch({}, {'on' 'off'}, 'exact')
ans =

Octave 4.4.0 (--traditional)
strmatch({}, {'on' 'off'}, 'exact')
error: strmatch: S must be a string

Arnaud Delorme <arnodelorme>
Thu 02 Aug 2018 04:22:28 PM UTC, original submission:  

Under Matlab 2018a

strmatch( '', {'a' 'b' 'c' })

ans =


Under Octave 4.4.0

strmatch( '', {'a' 'b' 'c' })

ans = []

Arnaud Delorme <arnodelorme>


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    Follow 6 latest changes.

    Date Changed by Updated Field Previous Value => Replaced by
    2018-08-03 rik5 Priority5 - Normal => 3 - Low
        StatusNeed Info => Confirmed
        Summarystrmatch incompatibilities with Matlab => strmatch incompatibilities with Matlab when using empty inputs
    2018-08-02 rik5 StatusNone => Need Info
        Operating SystemMac OS => Any
        Summarystrmatch => strmatch incompatibilities with Matlab

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