bugGNU Octave - Bugs: bug #53924, ismember error with mixed numeric...

 
 

bug #53924: ismember error with mixed numeric and char arrays inputs

Submitted by:  Guillaume <gyom>
Submitted on:  Wed 16 May 2018 11:03:42 AM UTC  
 
Category:  Octave Function Severity:  3 - Normal
Priority:  5 - Normal Item Group:  Matlab Compatibility
Status:  Fixed Assigned to:  None
Originator Name:  Guillaume Open/Closed:  Closed
Release:  dev Operating System:  Any

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Fri 14 Dec 2018 05:03:45 PM UTC, comment #4: 

I checked in the patch from comment #1 under your name here https://hg.savannah.gnu.org/hgweb/octave/rev/00924e6e513e.

Marking as fixed and closing report.

Rik <rik5>
Project Administrator
Fri 14 Dec 2018 09:50:58 AM UTC, comment #3: 

Matlab does this:

>> ismember (98, 'abc')
ans =
  logical
   1
>> ismember ('abc', 98)
ans =
  1x3 logical array
   0   1   0

Guillaume <gyom>
Fri 14 Dec 2018 01:26:41 AM UTC, comment #2: 

@Guillaume: does Matlab always promote to numeric?  Or does it depend on whether the input is the first or the second?

What does Matlab return for

ismember (98, 'abc')
ismember ('abc', 98)

Rik <rik5>
Project Administrator
Fri 18 May 2018 11:48:42 AM UTC, comment #1: 

It seems that when one input is numeric and the other is a char array, Matlab converts the latter into numeric so I suggest the following fix:

--- a/scripts/set/ismember.m    Sun Sep 04 16:09:43 2016 +0100
+++ b/scripts/set/ismember.m    Fri May 18 12:45:08 2018 +0100
@@ -108,6 +108,13 @@
     a = {a};
   endif

+  ## Another Matlab-compatible behavior. See bug #53924.
+  if (isnumeric (a) && ischar (s))
+    s = double (s);
+  elseif (ischar (a) && isnumeric (s))
+    a = double (a);
+  endif
+
   [a, s] = validsetargs ("ismember", a, s, varargin{:});

   by_rows = nargin == 3;
@@ -165,12 +172,15 @@
%!assert (ismember ("abc", {"abc", "def"}), true)
%!assert (isempty (ismember ([], [1, 2])), true)
%!assert (isempty (ismember ({}, {'a', 'b'})), true)
+%!assert (isempty (ismember ([], 'a')), true)
%!assert (ismember ("", {"abc", "def"}), false)
+%!assert (ismember (1, 'abc'), false)
+%!assert (ismember ('abc', 1), [false false false])
+%!assert (ismember ('abc', 99), [false false true])
%!fail ("ismember ([], {1, 2})")
%!fail ("ismember ({[]}, {1, 2})")
%!fail ("ismember ({}, {1, 2})")
%!fail ("ismember ({1}, {'1', '2'})")
-%!fail ("ismember (1, 'abc')")
%!fail ("ismember ({'1'}, {'1' '2'},'rows')")
%!fail ("ismember ([1 2 3], [5 4 3 1], 'rows')")
%!assert (ismember ({"foo", "bar"}, {"foobar"}), [false false])

Guillaume <gyom>
Wed 16 May 2018 11:03:42 AM UTC, original submission:  

Unusual corner case with ismember() but it highlights a difference between Octave and Matlab.

In Octave:

octave> ismember([],'a')
error: Invalid call to lookup.  Correct usage is:
-- IDX = lookup (TABLE, Y)
-- IDX = lookup (TABLE, Y, OPT)
error: called from
    print_usage at line 91 column 5
    ismember at line 136 column 10

In Matlab:

>> ismember([],'a')
ans =
  0x0 empty logical array

Testing further, one also gets in Octave:

octave> ismember([],{'a'})
ans = [](0x0)

while Matlab gives an error:

>> ismember([],{'a'})
Error using cell/ismember (line 34)
Input A of class double and input B of class cell must be cell arrays of character vectors, unless one is a
character vector.

Guillaume <gyom>

 

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    Follow 3 latest changes.

    Date Changed by Updated Field Previous Value => Replaced by
    2018-12-14 rik5 StatusPatch Submitted => Fixed
        Open/ClosedOpen => Closed
    2018-12-14 rik5 StatusNone => Patch Submitted

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