Re: [R] problem with for()

From: Marc Schwartz <MSchwartz_at_mn.rr.com>
Date: Thu 04 Aug 2005 - 08:39:55 EST

It would help to have an example of what it is you are trying to do.

Importantly, keep separate the need to have zero be a value in a vector as opposed to using zero to index a vector.

As I note below in my reply, you can have:

> x <- 0:5

> x

[1] 0 1 2 3 4 5

> x ^ 2

[1] 0 1 4 9 16 25

Marc

On Thu, 2005-08-04 at 00:25 +0200, Simone Gabbriellini wrote:
> how can I have a 0 evaluated in my loop then?
> it is important for my algorithm
>
> do you have any hints?
>
> simone
>
> Il giorno 03/ago/05, alle ore 23:37, Marc Schwartz ha scritto:
>
> > On Wed, 2005-08-03 at 23:24 +0200, Simone Gabbriellini wrote:
> >
> >> Dear list,
> >> can someone tell me why this two pieces of code give me the same
> >> results?
> >>
> >>
> >>> for(i in 0:5){ sum[i] = i }
> >>> sum
> >>>
> >> [1] 1 2 3 4 5
> >>
> >>
> >>> for(i in 1:5){ sum[i] = i }
> >>> sum
> >>>
> >> [1] 1 2 3 4 5
> >>
> >> shouldn't the first one be
> >>
> >> 0 1 2 3 4 5
> >>
> >> thank you,
> >> simone
> >>
> >
> > No....the indexing of R objects is 1 based. Thus your first loop tried
> > to set i[0], which is a non-existent entry.
> >
> >
> >> i <- 0:5
> >>
> >
> >
> >> i
> >>
> > [1] 0 1 2 3 4 5
> >
> >
> >> i[0]
> >>
> > numeric(0)
> >
> >
> >> i[1]
> >>
> > [1] 0
> >
> > HTH,
> >
> > Marc Schwartz
> >
> >
> >
> >



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