[Rd] Save R Objects in C Code

[Ziqiang Zhao]

Thanks for your help.
Since I don't know how to reference the current environment, I create a new
one to do so.
It seems that it works.
Not sure if it is helpful to anyone else out there, but here is my solution:
SEXP Save(SEXP X,SEXP File)
{
	char Name='X';

	SEXP EnvList;
	PROTECT(EnvList=allocList(1));
	SET_TAG(EnvList,install(&Name));
	SETCAR(EnvList,X);

	SEXP Env;
	PROTECT(Env=allocSExp(ENVSXP));
	SET_FRAME(Env,EnvList);
	SET_ENCLOS(Env,R_BaseEnv);
	SET_HASHTAB(Env,R_NilValue);
	SET_ATTRIB(Env,R_NilValue);

	int L=length(STRING_ELT(File,0));

	char *CMD=(char *)malloc((L+18)*sizeof(double));
	CMD[0]='s';CMD[1]='a';
CMD[2]='v';CMD[3]='e';CMD[4]='(';CMD[5]='X';CMD[6]=',';CMD[7]='f';CMD[8]='i'
;CMD[9]='l';CMD[10]='e';CMD[11]='=';CMD[12]='"';
	for(int k=0;k<L;k++)
	{
		CMD[k+13]=CHAR(STRING_ELT(File,0))[k];
	}
	CMD[L+13]='"';	CMD[L+14]=')';	CMD[L+15]=';';
CMD[L+16]='\n';CMD[L+17]='\0';

	SEXP RCMD,REXP;
	PROTECT(RCMD=allocVector(STRSXP,1));
	SET_STRING_ELT(RCMD,0,mkChar(CMD));
	ParseStatus Status;
	REXP=PROTECT(R_ParseVector(RCMD,-1,&Status,R_NilValue));
	eval(VECTOR_ELT(REXP,0),Env);
	UNPROTECT(4);
	return R_NilValue;
}

--------------------
Ziqiang Zhao
2013-06-29

-----Original Message-----
From: Prof Brian Ripley [mailto:ripley at stats.ox.ac.uk] 
Sent: Wednesday, June 26, 2013 4:32 PM
To: johnzhao2835 at gmail.com
Cc: r-devel at r-project.org
Subject: Re: [Rd] Save R Objects in C Code

On 26/06/2013 09:17, Ziqiang Zhao wrote:
> Dear all,
>
>                  How do I save the R objects in C code?
>
>                  In R code, we use save(x,y,file="F.RData") to save x 
> and y in "F.RData".
>
>                  But what should I do in C?

Call that R code (using eval).

If you look at the R code for save() you will see that a substantial amount
of it is interpreted code.

>
> --------------------
>
> Ziqiang Zhao
>
> 2013-06-26
>
>
>
>
> 	[[alternative HTML version deleted]]

Please see the posting guide and what it says about HTML mail.

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595