[Octave-bug-tracker] [bug #36236] Boolean indexing not too prominent in the docs.

[Alexander Klein]

Follow-up Comment #3, bug #36236 (project octave):

Hello,

I just found some time to fix the documentation concerning boolean indexing,
and wondered if the following is intended behaviour:

octave:44> a=rand(5)
a =

   0.590252   0.785107   0.789109   0.973847   0.037473
   0.720128   0.552948   0.529387   0.712228   0.285633
   0.097387   0.498243   0.368774   0.341973   0.272160
   0.302804   0.645076   0.383922   0.550020   0.883258
   0.181661   0.969068   0.376169   0.458497   0.294898

octave:45> b=a(1:3,1:3)>0.5
b =

   1   1   1
   1   1   1
   0   0   0

octave:46> a(b)
ans =

   0.59025
   0.72013
   0.30280
   0.18166
   0.55295
   0.49824

octave:47> a(1:rows(b),1:columns(b))(b)
ans =

   0.59025
   0.72013
   0.78511
   0.55295
   0.78911
   0.52939

octave:48> a(rand(7)>0.5)
error: A(I): index out of bounds; value 48 out of bound 25
octave:48> a(-rand(7)>0.5)
ans = [](0x1)

So, what we get in more than one dimension is
vec(<array>)(find(vec(<boolean>))), which is OK, and seems to be the only way
to go for equally sized arrays and boolean indices, but we get index errors
only for out of bounds true indices, and puzzling results without a warning
when the indexing array is smaller than the indexed array.

Is this really what we want?

Alex

    _______________________________________________________

Reply to this item at:

  <http://savannah.gnu.org/bugs/?36236>

_______________________________________________
  Nachricht gesendet von/durch Savannah
  http://savannah.gnu.org/