R help - Mar 2008 - joining matrices, vectors, scalars in one object

Hi,

I have:

a <- matrix(c(0,1,0,1),nrow=2)
b <- matrix(c(1,1,1,0,0,0),nrow=3)
c <- 1
d <- c(1,0,1)

And I would like to join them in an object 'thing' so that I can  
access a, b, c, or d through an index in a for loop.

For example:
thing[4]
would return
[1]  1  0  1

Note however, that I have many of these 'thing' components. So many  
that  a command like

thing <- list(a = matrix(c(0,1,0,1),nrow=2), b = matrix(c 
(1,1,1,0,0,0),nrow=3), c = 1, d = c(1,0,1))

would become long and awkward.

Is there a way of declaring an empty 'thing' of a given length and  
then assigning its elements from a for loop? I need to allow elements  
a, b, c... that can be scalars, vectors or matrices with varying  
dimensions.

Thanks!

Gonçalo


	[[alternative HTML version deleted]]

You want to do 

thing <- list()    # empty thing
for ( i in 1:100 ) { 
  thing[[i]] <- ?????
}

But where is ????? coming from? If you can index it with an integer
then it is exactly coming from the kind of object you want to create. 
Chicken-egg problem. No?

G.

On Thu, Mar 13, 2008 at 09:04:11AM -0400, Gon?alo Ferraz
wrote:
> Hi,
> 
> I have:
> 
> a <- matrix(c(0,1,0,1),nrow=2)
> b <- matrix(c(1,1,1,0,0,0),nrow=3)
> c <- 1
> d <- c(1,0,1)
> 
> And I would like to join them in an object 'thing' so that I can  
> access a, b, c, or d through an index in a for loop.
> 
> For example:
> thing[4]
> would return
> [1]  1  0  1
> 
> Note however, that I have many of these 'thing' components. So many
> that  a command like
> 
> thing <- list(a = matrix(c(0,1,0,1),nrow=2), b = matrix(c 
> (1,1,1,0,0,0),nrow=3), c = 1, d = c(1,0,1))
> 
> would become long and awkward.
> 
> Is there a way of declaring an empty 'thing' of a given length and
> then assigning its elements from a for loop? I need to allow elements  
> a, b, c... that can be scalars, vectors or matrices with varying  
> dimensions.
> 
> Thanks!
> 
> Gon?alo
> 
> 
> 	[[alternative HTML version deleted]]
> 
> ______________________________________________
> R-help at r-project.org 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.

-- 
Csardi Gabor <csardi at rmki.kfki.hu>    UNIL DGM

I think you need:

thing <- vector("list", 4)
for (i in seq_along(thing)) {
    thing[[i]] <- # what you want to put here
}


Best,
Dimitris

----
Dimitris Rizopoulos
Biostatistical Centre
School of Public Health
Catholic University of Leuven

Address: Kapucijnenvoer 35, Leuven, Belgium
Tel: +32/(0)16/336899
Fax: +32/(0)16/337015
Web: http://med.kuleuven.be/biostat/
     http://www.student.kuleuven.be/~m0390867/dimitris.htm


----- Original Message ----- 
From: "Gon?alo Ferraz" <gferraz29 at gmail.com>
To: <r-help at stat.math.ethz.ch>
Sent: Thursday, March 13, 2008 2:04 PM
Subject: [R] joining matrices, vectors, scalars in one object


Hi,

I have:

a <- matrix(c(0,1,0,1),nrow=2)
b <- matrix(c(1,1,1,0,0,0),nrow=3)
c <- 1
d <- c(1,0,1)

And I would like to join them in an object 'thing' so that I can
access a, b, c, or d through an index in a for loop.

For example:
thing[4]
would return
[1]  1  0  1

Note however, that I have many of these 'thing' components. So many
that  a command like

thing <- list(a = matrix(c(0,1,0,1),nrow=2), b = matrix(c
(1,1,1,0,0,0),nrow=3), c = 1, d = c(1,0,1))

would become long and awkward.

Is there a way of declaring an empty 'thing' of a given length and
then assigning its elements from a for loop? I need to allow elements
a, b, c... that can be scalars, vectors or matrices with varying
dimensions.

Thanks!

Gon?alo


[[alternative HTML version deleted]]




--------------------------------------------------------------------------------

> ______________________________________________
> R-help at r-project.org 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.
> 

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