[R] Is there any performance difference between subset() and list comprehension?

Hello, Suppose that you have a data frame 'df' with variables 'V1', 'V2', 'V3', etc. Is there any (performance) difference (except the difference of the return types) between the following two computations? subset(df, V1 0, V2) and df$V2[df$V1 0] Best Regards, hyunjo

Re: [R] Is there any performance difference between subset() and list comprehension?

On Sat, 26 Sep 2009 15:26:12 +0900 You Hyun Jo youhyu...@gmail.com wrote: YHJ Is there any (performance) difference (except the difference of YHJ the return types) YHJ between the following two computations? Try it yourself. ?system.time is useful for that purpose. Stefan

Re: [R] Is there any performance difference between subset() and list comprehension?

Thanks, Stefan. I tested the expressions over a set of various size of data frames. The result shows 2) and 3) are faster than 1) especially over a data frame with a large number of columns. The third one is probably the best. 1) subset(df, V1 0, V2) or subset(df, V1 0, V2)$V2 2) df[df$V1