[R] Help in getting aggregated data

From: Deepak Manohar <deepakmanohar_at_gmail.com>
Date: Sat 31 Mar 2007 - 23:51:25 GMT


Hi team,

   I have the data of the form:

> a<- data.frame(x=c(1,2,1,4,3), y=c(1,2,1,4,3), z=c(1,2,3,4,5))

I need the output of the form

> b<- data.frame(x=c(1,2,3,4), y=c(1,2,3,4), z=(3,2,5,4) )

As you can see, the Z value contains the maximum for each of the (x,y) combinations.

I used
> c<-by(a$z, list(x=a$x, y=a$y), max)
> c[,]

   y
x 1 2 3 4
  1 3 NA NA NA
  2 NA 2 NA NA
  3 NA NA 5 NA
  4 NA NA NA 4

Not sure If I have any standard function to convert this to the data frame that I need. Can you help me convert the last array into the data frame? If there is any other way apart from using the "by" function, please inform me regarding that as well.


R-help@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 and provide commented, minimal, self-contained, reproducible code. Received on Sun Apr 01 09:56:24 2007

Archive maintained by Robert King, hosted by the discipline of statistics at the University of Newcastle, Australia.
Archive generated by hypermail 2.1.8, at Sun 01 Apr 2007 - 05:30:35 GMT.

Mailing list information is available at https://stat.ethz.ch/mailman/listinfo/r-help. Please read the posting guide before posting to the list.