Hi Andrew,
you can use strsplit for a character vector; you do not have to call it
for every element data$ComputerName[i].
If I understand correctly, maybe something like this helps
> ip <- "123.456.789.321" ## example data
> df <- data.frame(ip = rep(ip, 9), stringsAsFactors=FALSE)
> df
ip
1 123.456.789.321
2 123.456.789.321
3 123.456.789.321
4 123.456.789.321
5 123.456.789.321
6 123.456.789.321
7 123.456.789.321
8 123.456.789.321
9 123.456.789.321
>
> res <- unlist(strsplit(df[["ip"]], "\\."))
> ii <- seq(1, nrow(df)*4, by = 4)
> res[ii] ## A
[1] "123" "123" "123" "123" "123" "123" "123"
[8] "123" "123"
> res[ii+1] ## B
[1] "456" "456" "456" "456" "456" "456" "456"
[8] "456" "456"
> res[ii+2] ## C
[1] "789" "789" "789" "789" "789" "789" "789"
[8] "789" "789"
> res[ii+3] ## D
[1] "321" "321" "321" "321" "321" "321" "321"
[8] "321" "321"
Regards,
Enrico
Am 08.01.2012 11:06, schrieb Andrew Roberts:
Folks,
I have a data frame with 4861469 rows that contains an ip address
xxx.xxx.xxx.xxx as one of the columns. I want to assign a site to each
row based on IP ranges. To do this I have a function to split the ip
address as character into class A,B,C and D components. It works but is
horribly inefficient in terms of speed. I can't quite see how one of the
l/s/m/t/apply functions could be brought to bear on the problem. Does
anyone have any thoughts?
for(i in 1:4861469)
{
lst<-unlist(strsplit(data$ComputerName[i], "\\."))
data$IPA[i]<-lst[[1]]
data$IPB[i]<-lst[[2]]
data$IPC[i]<-lst[[3]]
data$IPD[i]<-lst[[4]]
rm(lst)
}
Andrew
Andrew Roberts
Children's Orthopaedic Surgeon
RJAH, Oswestry, UK
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--
Enrico Schumann
Lucerne, Switzerland
http://nmof.net/
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