hello,
The other day, I needed to repeat a values based on a sequence of another values; for e.g., a array of a,b,c needed to be repeated based on another array 3,2,1 and output needed to be a,a,a,b,b,c.
I started my R code with “for”…. then suddenly a booming voice echoed “If you are using “for” in R you aren’t using it properly”. So then I started thinking on how to do this without a loop;
Firstly, the code to repeat values based on a sequence of numbers using loops;
base<-c("a","b","c")
repetition<-c(3,2,1)
i<-1
x<-1:length(repetition)
new<-0
for(i in x){
new<-c(new,rep(base[i],repetition[i]))
i=i+1
}
new<-new[-c(1)]
new
Finally, the code to repeat values without sequence. The code is much cleaner, shorter and sweeter;
base<-c("a","b","c")
repetition<-c(3,2,1)
x<-data.frame(cbind(base,repetition))
x$repetition<-as.numeric(x$repetition)
rep_final<-rep(x$base,x$repetition)
rep_final
You can also use the na.locf function from zoo library for such cases. Say NO to Loops!!!!!!!
BIdesi 