[R] Evaluation of an expression as function argument

Sebastien Bihorel Sebastien.Bihorel at cognigencorp.com
Thu Apr 30 19:14:25 CEST 2009


Thanks Uwe and Baptiste

*Sebastien Bihorel, PharmD, PhD*
PKPD Scientist
Cognigen Corp
Email: sebastien.bihorel at cognigencorp.com 
<mailto:sebastien.bihorel at cognigencorp.com>
Phone: (716) 633-3463 ext. 323


Uwe Ligges wrote:
>
>
> Sebastien Bihorel wrote:
>> Dear R-users,
>>
>> I would like to know if is it possible to set a function argument as 
>> an evaluated expression. I have tried several syntaxes, including the 
>> following example, but could not get it anything to run. The plot 
>> function is used here but I would like to later apply the same 
>> approach to other functions.
>>
>> ##########################
>> items <- c(expression(col=2),expression(pch=2))
>>
>> for (in in seq(2)) {
>>  plot(1:10, eval(items[i]))
>> }
>> ##########################
>
> Way 1:
>
> for(i in seq(2))
>   do.call("plot", c(list(1:10), as.list(items[i])))
>
>
> Way 2 is perhaps easier for you:
>
>
> items <- list(col=2, pch=2)
> for (i in seq(2))
>   do.call("plot", c(list(1:10), items[i]))
>
>
> Ways 3...n up to others...
>
>
> Uwe Ligges
>
>
>
>
>>
>> Thanks in advance for your input.
>>
>> Sebastien
>>
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