R help - Jun 2010 - how to initial a list to store data result?

May I ask how to initialize a list?

usually I will use " result=list(0) "  to do this. is this right?

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On Mon, Jun 21, 2010 at 4:18 PM, song song <rprojecthelp at gmail.com>
wrote:
> May I ask how to initialize a list?
>
> usually I will use " result=list(0) " ?to do this. is this right?
It works, but it is cleaner to use

results=list()

The difference is that list(0) will have one component that contains
the number zero, whereas list() will simply initialize an empty list
(no components).

Peter

On Jun 21, 2010, at 7:18 PM, song song wrote:
> May I ask how to initialize a list?
>
> usually I will use " result=list(0) "  to do this. is this right?
There is now something in that list, namely an element whose value is  
zero. If you append to it with the c() function, the 0 will still be  
there.

 > result=list(0)
 > result=c(result, 5)
 > result
[[1]]
[1] 0

[[2]]
[1] 5

What's wrong with

result=list()
result=c(result, 5)

 > result
[[1]]
[1] 5


David Winsemius, MD
West Hartford, CT

Use
  result <- vector("list", n)
to make a list of length n, all of whose
components are NULL.

Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com  
> -----Original Message-----
> From: r-help-bounces at r-project.org 
> [mailto:r-help-bounces at r-project.org] On Behalf Of Peter Langfelder
> Sent: Monday, June 21, 2010 4:23 PM
> To: song song
> Cc: r-help at r-project.org
> Subject: Re: [R] how to initial a list to store data result?
> 
> On Mon, Jun 21, 2010 at 4:18 PM, song song 
> <rprojecthelp at gmail.com> wrote:
> > May I ask how to initialize a list?
> >
> > usually I will use " result=list(0) " ?to do this. is this
right?
> 
> It works, but it is cleaner to use
> 
> results=list()
> 
> The difference is that list(0) will have one component that contains
> the number zero, whereas list() will simply initialize an empty list
> (no components).
> 
> Peter
> 
> ______________________________________________
> 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.
>

The usual method is either

lis <- vector("list")

or, nearly equivalently,

lis <- list()

If you know in advance how many components the list will have, there can be a
slight advantage in using

lis25 <- vector("list", 25)

if e.g. you know the list will be of length 25.

Bill Venables.

 

-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org]
On Behalf Of song song
Sent: Tuesday, 22 June 2010 9:18 AM
To: r-help at r-project.org
Subject: [R] how to initial a list to store data result?

May I ask how to initialize a list?

usually I will use " result=list(0) "  to do this. is this right?

	[[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.