R Macro Question
On Wed, 29 Apr 2009, Jenn wrote:
Dear all,
I?am?a?new?R?user,?and?I?have?a?question?about?R?macro.
Here?is?the?situation,?I?want?to?do?item?option?analysis?(options?include:?A
,?B,?C,?D),?below?is?the?codes?for?option?A?analyses.
#option?A?analyses
optiona<-mat.or.vec(nrow(responsedata2),?ncol(responsedata2))
#?create?A?matrix?by?recoding
for?(i?in?1:ncol(responsedata2)){
??? optiona[,i]<-recode(responsedata2[,i],"'A'=1;NA=NA;else=0")
}
#?compute?mean?for?A?matrix
pa<-rep(0,ncol(optiona))
for?(i?in?1:ncol(optiona)){
??? pa[i]<-round(mean(optiona[,i],na.rm=TRUE),2)
}
pa1<-as.data.frame(pa)
?
I?can?repeat?the?codes?for?other?options such as "B", "C" and "D",?but?I?am?wondering?if?I?can?do?it?
in?a?macro?way--subsituting?"A"?"a"?in?the?codes?with?"B"?"b",?etc.
In?SAS?it?can?be?done?easily,?but?I?could?not?get?it?to?work?in?R.
I suspect that 'it' can also be done easily in R. But you have not really told the list what 'it' is. You should provide some R code that actually works- as the R Posting Guide recommends. The 'code' above is not syntactically valid R, so you haven't really run it and neither can we. The function 'recode' is not in base R, so you have to provide it or refer to the contributed package frmo which it is obtained. I can only guess what you are trying to do, but I'd say mapply() or one of its relatives (lapply, tapply, ... ) is probably equal to the type of task you wish to perform. HTH, Chuck
Waiting?for?your?reply. And?thank?you?so?much?in?advance. Meng [[alternative HTML version deleted]]
Charles C. Berry (858) 534-2098
Dept of Family/Preventive Medicine
E mailto:cberry at tajo.ucsd.edu UC San Diego
http://famprevmed.ucsd.edu/faculty/cberry/ La Jolla, San Diego 92093-0901