Re: how to vectorize it

[michaell]

Doug Stewart-4 wrote
> On Sun, Jul 21, 2019 at 5:51 PM shall689 <

> sahallacy@

> > wrote:
> 
>> shivax wrote
>> > hi, see this code:
>> >
>> >  input for example:
>> >
>> >  ris=[1 0 0;0 1 0;1 0 0; 0 1 1]
>> >  tit=[0 1 0 0]
>> >
>> >  tic
>> >  bb=0;
>> >  for hh=1:columns(ris)
>> >   bb=0;
>> >   for gg=1:rows(ris)
>> >     if tit(gg)
>> >          bb=0;
>> >         if ris(gg,hh)
>> >             bb=1;
>> >      endif
>> >     endif
>> >      ris(gg,hh)=bb;
>> >    endfor
>> >  endfor
>> >  toc
>> >
>> >
>> >
>> > it's possible to avoid loop?
>> >
>> >
>> >
>> > --
>> > Sent from:
>> > http://octave.1599824.n4.nabble.com/Octave-General-f1599825.html
>>
>>
> If you explain what you are trying to do, there might be a better way.
> 
> 
> 
> 
>> Here is what I understand of your very interesting problem.  Each row in
>> the
>> tit vector is associated with a row in the ris matrix.  All ris rows up
>> until the first tit row that equals 1 should be set to zero.  When a tit
>> row
>> = 1, the associated row in the ris vector should be copied and over write
>> all ris rows until tit row equals 1 again.
>>
>> I haven't been able to solve the problem, but I think repmat and find
>> might
>> be helpful.
>>
>> find(tit==1) will find the index of all the rows in tit that are equal to
>> 1
>> and repmat(ris(row,:),row,1) can be used to repeat a specific row in ris.
>>
>> If you can find the difference between the row index values of tit==1,
>> you
>> can determine how many times to repeat a specific row.
>>
>> If you find out how to vectorize this problem, could you please post the
>> solution.
>>
>> Thanks,
>> Stephen
>>
>>
>>
>> --
>> Sent from:
>> http://octave.1599824.n4.nabble.com/Octave-General-f1599825.html
>>
>>
>>
> 
> -- 
> DAS[image: Certificate for 206392]
> 
> <https://linuxcounter.net/user/206392.html>

ris=[zeros(1,size(ris,2));ris(tit==1,:)](1+cumsum(tit'),:);



--
Sent from: http://octave.1599824.n4.nabble.com/Octave-General-f1599825.html