[Octave-bug-tracker] [bug #60711] textscan with '.' char read as float

[Rik]

Update of bug #60711 (project octave):

        Operating System:       Microsoft Windows => Any                    

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Follow-up Comment #1:

There is a difference with Matlab, but Matlab's approach doesn't make as much
sense to me as Octave's.

Take a slightly different example for illustrative purposes.


q=textscan([',,2,,'],'%f','delimiter',',', 'emptyvalue', -1)


I specifically set the EmptyValue option to something besides NaN so the
processing of textscan is more obvious.  In both Octave and Matlab this
returns


q =
{
  [1,1] =

    -1
    -1
     2
    -1

}


This makes sense to me.  There is a missing value at the start of the string,
the second position is also missing, the third value is the number 2, and then
then there is another missing value.

Now try reading just a single '.' character.


textscan ('.', '%f')


Both Octave and Matlab return [] for this.

Based on this data, I would expect that ',,.,,' would be treated as EmptyValue
EmptyValue EmptyValue EmptyValue which is exactly what Octave does.  I'm not
sure why Matlab decides there are two values here when the delimiter was
clearly specified to be the comma ','.

Of course, if you have built your textscan parser to rely on this
Matlab-specific behavior then it will be a problem.  A simple hack would be to
use regular expressions and search&replace bare instances of '.' with
something else including possibly nothing.

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