[R] vectorizing an iterative process.

Geoffrey Zhu gzhu at peak6.com
Tue Dec 26 18:45:43 CET 2006


Yes, this solves my problem. Thanks for your help.

-----Original Message-----
From: Christos Hatzis [mailto:christos at nuverabio.com] 
Sent: Tuesday, December 26, 2006 10:58 AM
To: Geoffrey Zhu; r-help at stat.math.ethz.ch
Subject: RE: [R] vectorizing an iterative process.

In your case, the recurrence relationship for x can be solved easily:
Notice that 

sum{i=3D1,n}(x[i]-x[i-1]) =3D x[n] - x[0] 

and therefore

x[n] =3D x[0] + sum{i=3D1,n}(y[i-1] for n=3D1, N, with the appropriate initi=
al
condition for i=3D0, (x[0],y[0]).

Thus cumsum on y will give you a direct answer.

-Christos

Christos Hatzis, Ph.D.
Nuvera Biosciences, Inc.
400 West Cummings Park
Suite 5350
Woburn, MA 01801
Tel: 781-938-3830
www.nuverabio.com
 
  

-----Original Message-----
From: r-help-bounces at stat.math.ethz.ch
[mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Geoffrey Zhu
Sent: Tuesday, December 26, 2006 11:06 AM
To: r-help at stat.math.ethz.ch
Subject: Re: [R] vectorizing an iterative process.

I meant  x[i] <- x[i-1] + y[i-1] and Y[i] <- y[i-1] + x[i] below.

The mailing list software just keep adding 3D's. Sorry. 

-----Original Message-----
From: r-help-bounces at stat.math.ethz.ch
[mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Geoffrey Zhu
Sent: Tuesday, December 26, 2006 10:03 AM
To: Richard M. Heiberger; r-help at stat.math.ethz.ch
Subject: Re: [R] vectorizing an iterative process.

Hi Richard,

3D is automatically generated by the mailing list software, probably
because I had ] followed by =3D3D3D without a space in the original post. 

What I meant was to calculate x[i] =3D3D3D x[i-1] + y[i-1] 

For example, if X <- 1:10

Then I want the vector Y to be 1, 3, 6, 10, 15, 21, 28, 36, 45, 55, or
in other words Y[i] =3D3D3D y[i-1] + x[i]. 

Yes, cumsum does the trick for this. This is what I need. Thanks.

Just curious, do you know how to calculate the more generic x[i] <- f(
x[i-1], y[i-1] )?

Thanks,
Geoffrey



-----Original Message-----
From: Richard M. Heiberger [mailto:rmh at temple.edu]
Sent: Tuesday, December 26, 2006 9:56 AM
To: Geoffrey Zhu; r-help at stat.math.ethz.ch
Subject: Re: [R] vectorizing an iterative process.

> x[i]=3D3D3D3Dx[i-1]+y[i-1] for all i, how can I do this without a loop? 

It looks like
   x <- cumsum(y)

What does 3D mean?



_______________________________________________________=3D3D0A=3D3D
=3D3D0A=3D3D
=3D3D0A=3D3D
The information in this email or in any file attached hereto is=3D3D0A=3D3D
intended only for the personal and confidential use of the
individual=3D3D0A=3D3D or entity to which it is addressed and may contain
information that is=3D3D0A=3D3D proprietary and confidential. If you are not
the intended recipient of=3D3D0A=3D3D this message you are hereby notified
that any review, dissemination,=3D3D0A=3D3D distribution or copying of this
message is strictly prohibited. This communi=3D3D cation is for
information purposes only and should not be regarded as an off=3D3D er to
sell or as a solicitation of an offer to buy any financial product.
Em=3D3D ail transmission cannot be guaranteed to be secure or error-free.

______________________________________________
R-help at stat.math.ethz.ch mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.



_______________________________________________________=3D0A=3D
=3D0A=3D
=3D0A=3D
The information in this email or in any file attached hereto is=3D0A=3D
intended only for the personal and confidential use of the
individual=3D0A=3D or entity to which it is addressed and may contain
information that is=3D0A=3D proprietary and confidential. If you are not the
intended recipient of=3D0A=3D this message you are hereby notified that any
review, dissemination,=3D0A=3D distribution or copying of this message is
strictly prohibited. This communi=3D cation is for information purposes
only and should not be regarded as an off=3D er to sell or as a
solicitation of an offer to buy any financial product. Em=3D ail
transmission cannot be guaranteed to be secure or error-free.

______________________________________________
R-help at stat.math.ethz.ch mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.






_______________________________________________________=0A=
=0A=
=0A=
The information in this email or in any file attached hereto is=0A=
intended only for the personal and confidential use of the individual=0A=
or entity to which it is addressed and may contain information that is=0A=
proprietary and confidential. If you are not the intended recipient of=0A=
this message you are hereby notified that any review, dissemination,=0A=
distribution or copying of this message is strictly prohibited. This communi=
cation is for information purposes only and should not be regarded as an off=
er to sell or as a solicitation of an offer to buy any financial product. Em=
ail transmission cannot be guaranteed to be secure or error-free.



More information about the R-help mailing list