Re: [Rd] variable problem

From: Tom McCallum <tom.mccallum_at_levelelimited.com>
Date: Tue 07 Nov 2006 - 20:50:21 GMT

Works like a charm - thank you very much.

Tom

On Tue, 07 Nov 2006 20:45:04 -0000, Vladimir Dergachev <vdergachev@rcgardis.com> wrote:

> On Tuesday 07 November 2006 3:28 pm, Tom McCallum wrote:
>> Hi everyone,
>
> Hi Tom,
>
> Would this snippet work:
>
> for(i in 1:length(mylist))do.call(f, mylist[i])
>
> On the other hand it is not easy to see why you would want to call
> the
> same function with differently named arguments - perhaps what you are
> really
> trying to do has a different (and better) solution ?
>
> best
>
> Vladimir Dergachev
>
>>
>> I am not sure this is possible so I would be interested in your
>> responses. Say I have a variable 'v' with the string "myargument" in
>> and
>> I have a function 'f' that takes this argument as follows;
>>
>> f <- function( myargument=5 ) {
>> ... does something...
>> }
>>
>> Is there anyway I can say something like;
>>
>> f( v=10 ) such that it will be evaluated as f( myargument=10 ).
>>
>> I presume there may be some use eval and substitute but if someone could
>> point me in the right direction then that would be great.
>>
>> The end idea is to have a list of m items, declared somewhere else,
>> which
>> can be evaluated as particular arguments named after their list names
>>
>> e.g
>>
>> mylist <- list( "a"=1, "b"=2, "c"=3 )
>>
>> which can be passed to a function taking arguments a,b, or c and it will
>> be able to evaluate them accordingly :
>>
>> long hand this would evaluate to something like
>> f( a=mylist[["a"]] );
>> f( b=mylist[["b"]] );
>> f( c=mylist[["c"]] );
>>
>> but I would have actually rewritten something like
>> for ( myvar in names( mylist ) ) {
>> f( some_clever_substitution_to_act_as_argument(myvar) = mylist[[ myvar
>> ]] );
>> }
>>
>> I hope I have explained myself clearly enough, if not please say so and
>> I
>> will try and give a better example.
>>
>> Many thanks for your help
>>
>> Tom
>

-- 
Dr. Thomas McCallum
Systems Architect,
Level E Limited
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