Re: [R] Replace split with regex for speed ?
Thanks for your suggestions. Cheers, Chris -- View this message in context: http://r.789695.n4.nabble.com/Replace-split-with-regex-for-speed-tp3386098p3388958.html Sent from the R help mailing list archive at Nabble.com. __ R-help@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.
Re: [R] Replace split with regex for speed ?
Try this:
sub(\\.(\\d+)$, \\1, ts)
On Thu, Mar 17, 2011 at 11:01 PM, rivercode aqua...@gmail.com wrote:
Have timestamp in format HH:MM:SS.MMM.UUU and need to remove the last . so
it is in format HH:MM:SS.MMMUUU.
What is the fastest way to do this, since it has to be repeated on millions
of rows. Should I use regex ?
Currently doing it with a string split, which is slow:
head(ts)
[1] 09:30:00.000.245 09:30:00.000.256 09:30:00.000.633 09:30:00.001.309
09:30:00.003.635 09:30:00.026.370
ts = strsplit(ts, ., fixed = TRUE)
ts=lapply(ts, function(x) { paste(x[1], ., x[2], x[3], sep=) } ) #
Remove last . from timestamp, from HH:MM:SS.MMM.UUU to HH:MM:SS.MMMUUU
ts = unlist(ts)
Thanks,
Chris
--
View this message in context:
http://r.789695.n4.nabble.com/Replace-split-with-regex-for-speed-tp3386098p3386098.html
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__
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--
Henrique Dallazuanna
Curitiba-Paraná-Brasil
25° 25' 40 S 49° 16' 22 O
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Re: [R] Replace split with regex for speed ?
That's a good solution, but if you're really, really sure that the timestamps
are in the format you gave, it's quite a bit faster to use substr and paste,
because you don't have to do any searching in the string.
HTH
Rex
x = rep(09:30:00.000.633,100)
system.time(y-paste(substr(x,1,12),substr(x,14,16),sep=))
user system elapsed
0.870.000.88
system.time(y-sub(\\.(\\d+)$, \\1, x))
user system elapsed
1.650.001.65
system.time(y-sub(\\.(\\d+)$, \\1, x))
user system elapsed
1.650.001.66
system.time(y-paste(substr(x,1,12),substr(x,14,16),sep=))
user system elapsed
0.880.000.89
-Original Message-
From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] On
Behalf Of Henrique Dallazuanna
Sent: Friday, March 18, 2011 8:32 AM
To: rivercode
Cc: r-help@r-project.org
Subject: Re: [R] Replace split with regex for speed ?
Try this:
sub(\\.(\\d+)$, \\1, ts)
On Thu, Mar 17, 2011 at 11:01 PM, rivercode aqua...@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
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__
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and provide commented, minimal, self-contained, reproducible code.
--
Henrique Dallazuanna
Curitiba-Paraná-Brasil
25° 25' 40 S 49° 16' 22 O
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[R] 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.
__
R-help@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.
