[R] Converting character to function argument

[Henrik Bengtsson]

eval() and parse() are you friends here. Possibly also substitute().
Example:

 eval(parse(text="expand.grid(c(1,0),c(1,0))"))

However, I would like to reply with a question to you. Why do you end up
with a string that you need to convert in the first place? Maybe you are
more interested in a solution like the following one:

N <- 2
l <- lapply(1:N, FUN=function(x) c(0,1))
expand.grid(l)

Henrik Bengtsson
Lund University

> -----Original Message-----
> From: r-help-bounces at stat.math.ethz.ch 
> [mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of 
> Alvaro.Antonio.Novo at bportugal.pt
> Sent: den 12 september 2003 18:55
> To: r-help at stat.math.ethz.ch
> Subject: [R] Converting character to function argument
> 
> 
> How can one transform a character string into an argument of 
> a function (which is not or I don't want it to be a character string)?
> 
> Example:
> 
> > expand.grid(c(1,0),c(1,0)) ## OK
>   Var1 Var2
> 1    1    1
> 2    0    1
> 3    1    0
> 4    0    0
> 
> 
> > paste(rep("c(0,1)",2),collapse=',') ## to be used below
> [1] "c(0,1),c(0,1)"
> > ## string is the input I want, but it needs to be coerced to the 
> > correct
> format
> 
> > expand.grid(paste(rep("c(0,1)",2),collapse=',')) ## does not get me 
> > there
>            Var1
> 1 c(0,1),c(0,1)
> 
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