R help - Mar 2011 - Replace split with regex for speed ?

Have timestamp in format HH:MM:SS.MMM.UUU and need to remove the last
"." so
it is in format HH:MM:SS.MMMUUU.

What is the fastest way to do this, since it has to be repeated on millions
of rows. Should I use regex ?

Currently doing it with a string split, which is slow:

 >head(ts)
[1]  09:30:00.000.245  09:30:00.000.256  09:30:00.000.633  09:30:00.001.309 
09:30:00.003.635  09:30:00.026.370


  ts = strsplit(ts, ".", fixed = TRUE)
  ts=lapply(ts, function(x) { paste(x[1], ".", x[2], x[3],
sep="") } ) 	#
Remove last . from timestamp, from HH:MM:SS.MMM.UUU to HH:MM:SS.MMMUUU
  ts = unlist(ts)

Thanks,
Chris

--
View this message in context:
http://r.789695.n4.nabble.com/Replace-split-with-regex-for-speed-tp3386098p3386098.html
Sent from the R help mailing list archive at Nabble.com.

Try this:

 sub("\\.(\\d+)$", "\\1", ts)


On Thu, Mar 17, 2011 at 11:01 PM, rivercode <aquanyc at gmail.com>
wrote:
>
> Have timestamp in format HH:MM:SS.MMM.UUU and need to remove the last
"." so
> it is in format HH:MM:SS.MMMUUU.
>
> What is the fastest way to do this, since it has to be repeated on millions
> of rows. Should I use regex ?
>
> Currently doing it with a string split, which is slow:
>
> ?>head(ts)
> [1] ?09:30:00.000.245 ?09:30:00.000.256 ?09:30:00.000.633 ?09:30:00.001.309
> 09:30:00.003.635 ?09:30:00.026.370
>
>
> ?ts = strsplit(ts, ".", fixed = TRUE)
> ?ts=lapply(ts, function(x) { paste(x[1], ".", x[2], x[3],
sep="") } ) ?#
> Remove last . from timestamp, from HH:MM:SS.MMM.UUU to HH:MM:SS.MMMUUU
> ?ts = unlist(ts)
>
> Thanks,
> Chris
>
> --
> View this message in context:
http://r.789695.n4.nabble.com/Replace-split-with-regex-for-speed-tp3386098p3386098.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> R-help at r-project.org 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.
>


-- 
Henrique Dallazuanna
Curitiba-Paran?-Brasil
25? 25' 40" S 49? 16' 22" O