[R] newbie's question about dataframe

[Uwe Ligges]

Liaw, Andy wrote:
> Something like this should do it:
> 
>  dat$Z <- with(dat, as.numeric(Y >= Y[order(Y, decreasing=TRUE)[10]]))

I was just about to post

   dat$Z <- as.numeric(rank(-dat$Y) <= 10)

so here it is, anyway. ;-)


Uwe



> Andy
> 
> 
>>From: Wensui Liu
>>
>>I have a dataframe containing X and Y. Right now, I want to create
>>another variable in the dataframe, named Z, such that for Z = 1 for
>>the top 10 largest value of Y and Z = 0 for the rest values of Y.
>>
>>I really appreciate your help. Have a great weekend.
>>
>>______________________________________________
>>R-help at stat.math.ethz.ch mailing list
>>https://stat.ethz.ch/mailman/listinfo/r-help
>>PLEASE do read the posting guide! 
>>http://www.R-project.org/posting-guide.html
>>
>>
>>
> 
> 
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