Re: Nested R-expressions in r..eal

Dear Wouter, 

On Tue, 1 Oct 2013 16:32:31 +0200
Wouter Beek <[email protected]> wrote:

> Hi all,
> 
> I have a question regarding the r..eal package for R-integration in
> SWI-Prolog. Is it possible (and if so how) to nest R expressions in R
> expressions.
> 
> In [1] I would like to specify the margin parameter so that the label of
> the Y-axis does not interfere with the value labels of that axis.
> ~~~
> [1]   <- barplot(Bars, par(mar=[5,5,1,1]), ylab=+Y_Axis)
> [2]   <-barplot(Bars, "par(mai=c(1,1,1,1))", ylab=+Y_Axis)
> ~~~
> 
> The problem that I experience is that [2] works, but [1] does not. Any
> ideas on this?
> 
	version [2] seemingly works, but it probably does not do what you expect

	real can use debug library to show what is passed to R
	turn this on via ?- debug(real).
	in [2] above "par..." is passed as a vector of integer values 
	which is intepreted as parameter 'width' by barplot()
        that is the codes of your string are paseed not the intended c(1,1,1,1)

	i think there is something problematic with the underlying R statement 
	in your example

	the following is typed in R  (3.0.1) 

> barplot( c(1,2,3), par(mai=c(1,1,1,1) ) )
Error in width/2 : non-numeric argument to binary operator
In addition: Warning message:
In mean.default(width) : argument is not numeric or logical: returning NA
>

Could you provide a working R statement ?

Hope it helps,

Nicos Angelopoulos.