R help - Oct 2003 - assign a constant to a different column for each row

Hi all

I want to assign a constant to a different column for each row

eg:

m[1,2] <- 0;
m[2,3] <- 0;
m[3,1] <- 0;
m[4,2] <- 0;
m[5,1] <- 0;
...

etc...
          
i've tried apply/tapply with no luck

and also the following

coefs <- rtt.abs[,5:8];
coefs.i <- coefs[] == 1;
coefs[coefs.i] <- 0;

wich results in

"matrix subscripts not allowed in replacement" 

error message, for wich I have not found any workaround

a trivial for() loop is not fast enough

any help would be greatly appreciated, (maybe a gun too) I'm disperated :-\

Thanks in advance

	Ulisses


                Debian GNU/Linux: a dream come true
-----------------------------------------------------------------------------
"Computers are useless. They can only give answers."            Pablo
Picasso

--->	Visita http://www.valux.org/ para saber acerca de la	<---
--->	Asociaci?n Valenciana de Usuarios de Linux		<---

m[1:5 + nrow(m)*c(2,3,1,2,1)] <- 0 if m is a matrix.  Remember you can 
index a matrix as a vector.

If m is a data frame (you didn't say what it is)  I would loop over 
columns (not rows) explicitly, since the code is going to do that 
implicitly.

On Mon, 27 Oct 2003 uaca at alumni.uv.es wrote:
> 
> Hi all
> 
> I want to assign a constant to a different column for each row
> 
> eg:
> 
> m[1,2] <- 0;
> m[2,3] <- 0;
> m[3,1] <- 0;
> m[4,2] <- 0;
> m[5,1] <- 0;
> ...
> 
> etc...
>           
> i've tried apply/tapply with no luck
> 
> and also the following
> 
> coefs <- rtt.abs[,5:8];
> coefs.i <- coefs[] == 1;
> coefs[coefs.i] <- 0;
> 
> wich results in
> 
> "matrix subscripts not allowed in replacement" 
> 
> error message, for wich I have not found any workaround
> 
> a trivial for() loop is not fast enough
> 
> any help would be greatly appreciated, (maybe a gun too) I'm disperated
:-\
-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

Hi again

Thanks all for your fast! reply

regards

	Ulisses

                Debian GNU/Linux: a dream come true
-----------------------------------------------------------------------------
"Computers are useless. They can only give answers."            Pablo
Picasso

--->	Visita http://www.valux.org/ para saber acerca de la	<---
--->	Asociaci?n Valenciana de Usuarios de Linux		<---

uaca at alumni.uv.es wrote:
> Hi all
> 
> I want to assign a constant to a different column for each row
> 
> eg:
> 
> m[1,2] <- 0;
> m[2,3] <- 0;
> m[3,1] <- 0;
> m[4,2] <- 0;
> m[5,1] <- 0;
> ...
> 
> etc...
>           
> i've tried apply/tapply with no luck
> 
> and also the following
> 
> coefs <- rtt.abs[,5:8];
> coefs.i <- coefs[] == 1;
> coefs[coefs.i] <- 0;
> 
> wich results in
> 
> "matrix subscripts not allowed in replacement" 
> 
> error message, for wich I have not found any workaround
> 
> a trivial for() loop is not fast enough
> 
> any help would be greatly appreciated, (maybe a gun too) I'm disperated
:-\
> 
> Thanks in advance
> 
> 	Ulisses
> 
> 
>                 Debian GNU/Linux: a dream come true
>
-----------------------------------------------------------------------------
> "Computers are useless. They can only give answers."           
Pablo Picasso
> 
> --->	Visita http://www.valux.org/ para saber acerca de la	<---
> --->	Asociaci?n Valenciana de Usuarios de Linux		<---
> 
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://www.stat.math.ethz.ch/mailman/listinfo/r-help
> 
> 
 > cbind(c(1,2,3),c(4,5,6),c(6,7,8))->l
 > l
      [,1] [,2] [,3]
[1,]    1    4    6
[2,]    2    5    7
[3,]    3    6    8
 > l[1:2,1:3]<-4
 > l
      [,1] [,2] [,3]
[1,]    4    4    4
[2,]    4    4    4
[3,]    3    6    8
 >