Background:
I use R for a fair-sized graphics program, intended for naïve users. This
works,
but a less-naïve user wants it to generate code producing the graphs that he
can
then modify (but which will not contain my numerous manipulations and attempts
to
discern what the user wants).
Quite possibly this is a standard R activity, but I've been unable to find it;
likely I have a mental block about search terms.
The natural way to do this seems _to_me_ to be to create wrapper functions for
R's graphics functions, each of which will, if needed, echo the call to a file.
Then I need only replace graphics function calls with wrapper function calls,
and
can avoid complicating my program enormously. Is there something better that
will
maintain this goal? (If it's relevant, I'm reluctant to tell my naïve users to
download packages.)
Main question:
My version of a wrapper function, in some valid code(*), follows; I would like
to simplify
it if I can. (other attempts fell down trying to handle the ... argument that
many
graphics functions have, probably because I fail to understand the use of ...)
I'm also nervous that my approach may fail to work for some functions; is there
a hidden flaw?
(*) but you'll have to change the file reference in OnyxEchoFile
esegments<-function(x0, y0, x1=x0, y1=y0, col=par("fg"), lty=par("lty"),
lwd=par("lwd"), ...)
{
# collect the call as a suitable list, using match.call
TheCallList <- as.list(match.call())
# turn it into (list version of) a call to the graphics function we actually
want
TheCallList[[1]]<-quote(segments)
# replace the variable names used with their values
# (because I do not wish to record all the messy calculation I do)
if (length(TheCallList)>1)
{
for (iarg in seq(2, length(TheCallList)))
{
TheCallList[[iarg]]<-eval(TheCallList[[iarg]])
}
}
# make it back into a call
TheCall<-as.call(TheCallList)
# and finally call it
ToReturn<-eval(TheCall)
# and the purpose of the whole shebang is to be able to record the
# raw graphics call for posterity
if (DoOnyxEcho==TRUE) capture.output(TheCall, file=OnyxEchoFile, append=TRUE)
# mimic the return from segments (NULL in this case, but not generally)
invisible(ToReturn)
}
DoOnyxEcho<-TRUE
OnyxEchoFile<-"d:\\ftp\\echotest.r"
plot(1:20)
start<-10
end<-15
esegments(start, start, end, end, lty="dashed", lend=2)
Thank you!
- Paul Sherliker
______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
