[R] creating list with 200 identical objects

[Rainer M Krug]

On Mon, Jun 1, 2009 at 12:19 PM, Romain Francois
<romain.francois at dbmail.com> wrote:
> Hi,
>
> Here are a few ways:

Thanks - I like it when I have a choice.

>
> rep( list( new("track") ), 5 )

OK - This one is executing new("track") once, and copying it into a list.

> lapply( 1:5, function(x) new("track") )

This one executes new("track") five times and creates the list.

no <- new("track")
lapply( 1:5, function(x) return(no))

should do the same, only faster, as new() is executed only once.

> list( new("track") ) [ rep(1, 5 ) ]

now this is a really sneaky one - I like it, although it is the most
difficult to understand.

Thanks for these options. I think I will go with the first one, as it
is the most intuitive one.

Thanks,

Rainer

>
> Romain
>
> Rainer M Krug wrote:
>>
>> Hi
>>
>> I am doing an simulation, and I a large proportion of the simulation
>> time is taken up by memory allocations.
>>
>> I am creating an object, and storing it in a list of those objects.
>>
>> essentially:
>>
>> x <- list()
>> for (t in 1:500) {
>>  x[1] <- new("track")
>> }
>>
>> I would like to initialize in one go, to avoid the continuous
>> reallocation of memory when a new "track" is added, and fill it wit
>> the object created by new("track").
>>
>> How can I do this?
>>
>> thanks
>>
>> Rainer
>>
>
>
> --
> Romain Francois
> Independent R Consultant
> +33(0) 6 28 91 30 30
> http://romainfrancois.blog.free.fr
>
>
>



-- 
Rainer M. Krug, Centre of Excellence for Invasion Biology,
Stellenbosch University, South Africa