Thread Subject: Vectorization

Is it possible to vectorize the following for - if - loop?

x=randn(10,1);
thres=0.1;
y=zeros(10,1);
for i=1:10
    if x(i) > thres
        y(i) = 1;
    end
end

Thanks for help.

"Daniel " <d@f.com> wrote in message
<g2r957$lr1$1@fred.mathworks.com>...
> Is it possible to vectorize the following for - if - loop?
>
> x=randn(10,1);
> thres=0.1;
> y=zeros(10,1);
> for i=1:10
> if x(i) > thres
> y(i) = 1;
> end
> end
>
> Thanks for help.
Yes, use logical indexing. In stead of the loop, use:
y(x>thres) = 1;

Greetz,
Sebastiaan

Or:

   y = (x>thres);


Rick


"Sebastiaan " <s.breedveld@erasmusmc.REMOVE.BOO.BOO.nl> wrote in message
news:g2ra6u$3tf$1@fred.mathworks.com...
> "Daniel " <d@f.com> wrote in message
> <g2r957$lr1$1@fred.mathworks.com>...
>> Is it possible to vectorize the following for - if - loop?
>>
>> x=randn(10,1);
>> thres=0.1;
>> y=zeros(10,1);
>> for i=1:10
>> if x(i) > thres
>> y(i) = 1;
>> end
>> end
>>
>> Thanks for help.
> Yes, use logical indexing. In stead of the loop, use:
> y(x>thres) = 1;
>
> Greetz,
> Sebastiaan
>

"Daniel " <d@f.com> writes:

> Is it possible to vectorize the following for - if - loop?
>
> x=randn(10,1);
> thres=0.1;
> y=zeros(10,1);
> for i=1:10
> if x(i) > thres
> y(i) = 1;
> end
> end

x=randn(10,1);
thres=0.1;
y = x>thres;

If you need y to be non-logical, then:

y = double(x>thres);

-Peter

"Daniel " <d@f.com> wrote in message <g2r957$lr1
$1@fred.mathworks.com>...
> Is it possible to vectorize the following for - if -
loop?
>
> x=randn(10,1);
> thres=0.1;
> y=zeros(10,1);
> for i=1:10
> if x(i) > thres
> y(i) = 1;
> end
> end
>
> Thanks for help.

Here is another one:

arrayfun(@(t)t>thres,x)

Peter Boettcher <boettcher@ll.mit.edu> wrote in message
<muyfxri3fim.fsf@G99-Boettcher.llan.ll.mit.edu>...
> "Daniel " <d@f.com> writes:
>
> > Is it possible to vectorize the following for - if -
loop?
> >
> > x=randn(10,1);
> > thres=0.1;
> > y=zeros(10,1);
> > for i=1:10
> > if x(i) > thres
> > y(i) = 1;
> > end
> > end
>
> x=randn(10,1);
> thres=0.1;
> y = x>thres;
>
> If you need y to be non-logical, then:
>
> y = double(x>thres);
>
> -Peter


Just for fun, to show the values that are bigger than
thres:

x(x>thres)