Match dates and id between data.frames only once - r

Question

Have 2 example databases as follows
id<-c(1,2,3,1,4,3,5)
date<-c("2011-1-1","2011-1-1","2011-2-2","2012-3-3","2012-4-4","2012-5-5","2012-6-6")
d<-data.frame(cbind(id,date))
colnames(d)<-c("id","date")
d$w<-do.call(paste,c(d[c("id","date")],sep=" "))
id<-c(7,8,9,10,7,10,8,10,11,12)
date<-c("2011-1-1","2011-1-1","2011-2-2","2012-3-3","2012-3-3","2012-4-4","2012-4-4","2012-5-5","2012-6-6","2012-6-6")
contr<-data.frame(cbind(id,date))
colnames(contr)<-c("id","date")
contr$w<-do.call(paste,c(contr[c("id","date")],sep=" "))
Consider that id and dates are repeated in both datasets but d$id are all different from contr$id and that all contr$date are %in% d$date
What I want is y that is a vector including ONE contr$w FOR EACH d$id that have a contr$date%in%d$date
I have tried this which does not work but I am sure there must be a much easier,simpler=better way to do it.
y<-0
for(i in length(levels(factor(d$w)))){
for(j in length(levels(factor(contr$w)))){
z<-ifelse(d$date[i]==contr$date[j],contr$w[j],NA)
y<-c(y,z)
y<-subset(y,!is.na(y))
}
}
Anyone can help?
Many thanks,
Marco

Answer 1

This did what I wanted, maybe I was not clear enough in my explanation. I just wanted a random date per id (then I can create the w column). I have sorted this by using a solution from this other question:
Random row selection in R
Many t
hanks for the effort anyway!
Marco

Answer 2

Actually I have written now a loop that does this (the previous answer did not work as some cases in d did not have a matching date in contr). It is very slow but it does exactly what I wanted
for(i in 1:length(d$rownames)){
if(TRUE%in%levels(factor(contr$w%in%d$w[i]))==TRUE){
control.2$rownames[i]<-sample(contr$rownames[ctr$w==d$w[i]],1)
contr<-contr[!contr$rownames%in%control.2$rownames[i],]
}else{
z<-contr[contr$practice==d$practice[i],]
z$tempo<-abs(difftime(z$date,d$date[i],units="days"))
z<-z[!is.na(z$tempo),]
z<-z[z$tempo==min(z$tempo),]
control.2$rownames[i]<-sample(z$rownames,1)
contr<-contr[!contr$rownames%in%control.2$rownames[i],]
}
}
Not the best code I am sure, but it works. The second look accounts for the few cases where there was no case with a matching date so I chose the sampled() one with the closest date. If you can come up with a faster version, that would be nice. My datasets are about d=~5K rows and contr=~2.5 million rows and it takes roughly 2 hours to run. Painful but worth the wait!