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strata
2012 Oct 10
3
practical to loop over 2million rows?
...eems that even with these speed ups I might have too much data to run
loops. Here is the loop I ran that took 13 minutes. I realize I can
accomplish the same goal using vectorization (and in fact did so).
y<-numeric(length(x))
for(i in 1:length(x))
ifelse(!is.na(x[i]), y[i]<-x[i],
ifelse(strataID[i+1]==strataID[i], y<-x[i+1], y<-x[i-1]))
Presumably, complicated loops would be more intensive than the nested if
statement above. If I write more efficient loops time will come down but I
wonder if I will ever be able to write efficient enough code to perform a
complicated loop over 2 mill...