[R] IP-Address

[Peter Dalgaard]

Allan Engelhardt wrote:
> IP addresses are very (very!) difficult to parse and sort correctly
> because there are all sorts of supported formats.  Try to use something
> like PostgreSQL instead: it is already implemented there.  But if you
> are sure all your data is of the n.n.n.n form, then something along the
> lines of the following should basically work (I have chosen some more
> interesting IP addresses for this):
> 
> 
> a <- data.frame(cbind(id=c(138,138,138,138),
>                      rank=c(29746,29746,29746,29746),
>                      color=c("yellow","red","blue","red"),
>                      status=c("no","yes","yes","no"),
>                     
> ip=c("162.131.58.26","2.131.58.16","2.2.58.10","162.131.58.17")))
> a
> #    id  rank  color status            ip
> # 1 138 29746 yellow     no 162.131.58.26
> # 2 138 29746    red    yes   2.131.58.16
> # 3 138 29746   blue    yes     2.2.58.10
> # 4 138 29746    red     no 162.131.58.17
> x <- matrix(unlist(lapply(strsplit(as.character(a$ip), ".", fixed=TRUE),
> as.integer)),
>            ncol=4, byrow=TRUE)
> a[order(x[,1],x[,2],x[,3],x[,4]),]
> #    id  rank  color status            ip
> # 3 138 29746   blue    yes     2.2.58.10
> # 2 138 29746    red    yes   2.131.58.16
> # 4 138 29746    red     no 162.131.58.17
> # 1 138 29746 yellow     no 162.131.58.26
> 
> 
> Getting rid of the conversions including the matrix(unlist) combo is
> left as an exercise (it's too hot here....)

Here's one way:

con <- textConnection(as.character(a$ip))
o <- do.call(order,read.table(con,sep="."))
close(con)
a[o,]


-- 
   O__  ---- Peter Dalgaard             Øster Farimagsgade 5, Entr.B
  c/ /'_ --- Dept. of Biostatistics     PO Box 2099, 1014 Cph. K
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~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)              FAX: (+45) 35327907