Re: [R] Replacing elements of a list over a certain threshold
> -Original Message- > From: r-help-boun...@r-project.org > [mailto:r-help-boun...@r-project.org] On Behalf Of David Winsemius > Sent: Tuesday, June 22, 2010 11:24 AM > To: johan...@huesing.name > Cc: r-help@r-project.org > Subject: Re: [R] Replacing elements of a list over a certain threshold > > > On Jun 22, 2010, at 2:14 PM, Johannes Huesing wrote: > > > Jim Hargreaves [Mon, Jun 21, 2010 at 12:34:01PM > > CEST]: > >> Dear List, > >> > >> I have a list of length ~1000 filled with numerics. I need to > >> replace the elements of this list that are above a certain > numerical > >> threshold with the value of the threshold. > >> > >> e.g > >> example=list(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 9, 8, 7, 6, 5, > 4, 3, 2, > >> 1) Is it essential that the dataset 'example' be a 'list' and not a 'numeric' object (created in this case by calling 'c' instead of 'list')? list's can contain elements of various types and there are usually time and memory penalties for allowing that flexibility. numeric (or character or complex or logical) objects contain only one type of element and generally use less space than the equivalent list and processing them generally takes less time. E.g., here are timings for several of the algorithms that have been suggested on equivalent list and numeric objects of length 10^5: > x.orig <- runif(10^5, min=0, max=10) # numeric object > xl.orig <- as.list(x.orig) # list object, one scalar numeric vector per element > x <- x.orig ; system.time(x[x>5] <- 5) user system elapsed 0.000 0.000 0.004 > x <- x.orig ; system.time(x <- pmin(x, 5)) user system elapsed 0.010 0.000 0.002 > xl <- xl.orig ; system.time(xl[xl>5] <- 5) user system elapsed 0.020 0.000 0.013 > xl <- xl.orig ; system.time(xl <- pmin(xl, 5)) user system elapsed 0.080 0.000 0.084 > xl <- xl.orig ; system.time(xl <- lapply(xl, min, 5)) user system elapsed 0.130 0.000 0.135 In addition to the time penalty, it just seems unnatural to use a list to store numbers when a numeric object could do the job. Bill Dunlap Spotfire, TIBCO Software wdunlap tibco.com > >> threshold=5 > >> > >> example=(1, 2, 3, 4, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 4, 3, 2, 1). > >> > > > > lapply(example, min, 5) > > Perhaps wrapped in unlist( ) if a vector is desired. > > The same strategy would work with pmin and probably be faster > (albeit > not a big deal if the list is only 1000 elements long: > > unlist( pmin(example, 5) ) > > > > > > -- > > Johannes Hüsing > > > David Winsemius, MD > West Hartford, CT > > __ > 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. > __ 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] Replacing elements of a list over a certain threshold
On Jun 22, 2010, at 2:14 PM, Johannes Huesing wrote: Jim Hargreaves [Mon, Jun 21, 2010 at 12:34:01PM CEST]: Dear List, I have a list of length ~1000 filled with numerics. I need to replace the elements of this list that are above a certain numerical threshold with the value of the threshold. e.g example=list(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1) threshold=5 example=(1, 2, 3, 4, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 4, 3, 2, 1). lapply(example, min, 5) Perhaps wrapped in unlist( ) if a vector is desired. The same strategy would work with pmin and probably be faster (albeit not a big deal if the list is only 1000 elements long: unlist( pmin(example, 5) ) -- Johannes Hüsing David Winsemius, MD West Hartford, CT __ 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] Replacing elements of a list over a certain threshold
Jim Hargreaves [Mon, Jun 21, 2010 at 12:34:01PM CEST]: > Dear List, > > I have a list of length ~1000 filled with numerics. I need to > replace the elements of this list that are above a certain numerical > threshold with the value of the threshold. > > e.g > example=list(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1) > threshold=5 > > example=(1, 2, 3, 4, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 4, 3, 2, 1). > lapply(example, min, 5) -- Johannes Hüsing There is something fascinating about science. One gets such wholesale returns of conjecture mailto:johan...@huesing.name from such a trifling investment of fact. http://derwisch.wikidot.com (Mark Twain, "Life on the Mississippi") __ 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] Replacing elements of a list over a certain threshold
Try this also: replace(example, example > threshold, threshold) On Mon, Jun 21, 2010 at 7:34 AM, Jim Hargreaves wrote: > Dear List, > > I have a list of length ~1000 filled with numerics. I need to replace the > elements of this list that are above a certain numerical threshold with the > value of the threshold. > > e.g > example=list(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1) > threshold=5 > > example=(1, 2, 3, 4, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 4, 3, 2, 1). > > I have written a crude script that achieves this but it's very slow. Is > there a way to do this using some R function? > > Crude script: http://pastebin.com/3KSfi8nD > > > __ > 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. > -- Henrique Dallazuanna Curitiba-Paraná-Brasil 25° 25' 40" S 49° 16' 22" O [[alternative HTML version deleted]] __ 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] Replacing elements of a list over a certain threshold
You shouldn't use sapply/lapply for this but use the indices > set.seed(1) > r <- round(runif(10,1,10)) > treshold <- 5 > head(r) [1] 3 4 6 9 3 9 > system.time( r[ r>threshold ] <- threshold ) user system elapsed 0 0 0 > head(r) [1] 3 4 5 5 3 5 On Mon, Jun 21, 2010 at 2:03 PM, Christos Argyropoulos wrote: > > Hi, > You should use the sapply/lapply for such operations. > >> r<-round(runif(10,1,10)) >> head(r) > [1] 3 7 6 3 2 8 >> filt<-function(x,thres) ifelse(x> system.time(r2<-sapply(r,filt,thres=5)) > user system elapsed > 3.36 0.00 3.66 >> head(r2) > [1] 3 5 5 3 2 5 > > > To return a list, replace "sapply" with "lapply" > > Christos > > > >> Date: Mon, 21 Jun 2010 11:34:01 +0100 >> From: ja...@ipec.co.uk >> To: r-help@r-project.org >> Subject: [R] Replacing elements of a list over a certain threshold >> >> Dear List, >> >> I have a list of length ~1000 filled with numerics. I need to replace >> the elements of this list that are above a certain numerical threshold >> with the value of the threshold. >> >> e.g >> example=list(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1) >> threshold=5 >> >> example=(1, 2, 3, 4, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 4, 3, 2, 1). >> >> I have written a crude script that achieves this but it's very slow. Is >> there a way to do this using some R function? >> >> Crude script: http://pastebin.com/3KSfi8nD >> >> __ >> 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. > > _ > Hotmail: Free, trusted and rich email service. > > [[alternative HTML version deleted]] > > __ > 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. > -- Joris Meys Statistical consultant Ghent University Faculty of Bioscience Engineering Department of Applied mathematics, biometrics and process control tel : +32 9 264 59 87 joris.m...@ugent.be --- Disclaimer : http://helpdesk.ugent.be/e-maildisclaimer.php __ 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] Replacing elements of a list over a certain threshold
Hi, You should use the sapply/lapply for such operations. > r<-round(runif(10,1,10)) > head(r) [1] 3 7 6 3 2 8 > filt<-function(x,thres) ifelse(x system.time(r2<-sapply(r,filt,thres=5)) user system elapsed 3.360.003.66 > head(r2) [1] 3 5 5 3 2 5 To return a list, replace "sapply" with "lapply" Christos > Date: Mon, 21 Jun 2010 11:34:01 +0100 > From: ja...@ipec.co.uk > To: r-help@r-project.org > Subject: [R] Replacing elements of a list over a certain threshold > > Dear List, > > I have a list of length ~1000 filled with numerics. I need to replace > the elements of this list that are above a certain numerical threshold > with the value of the threshold. > > e.g > example=list(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1) > threshold=5 > > example=(1, 2, 3, 4, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 4, 3, 2, 1). > > I have written a crude script that achieves this but it's very slow. Is > there a way to do this using some R function? > > Crude script: http://pastebin.com/3KSfi8nD > > __ > 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. _ Hotmail: Free, trusted and rich email service. [[alternative HTML version deleted]] __ 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] Replacing elements of a list over a certain threshold
"magic" code: example[example>threshold] <-threshold Cheers Joris On Mon, Jun 21, 2010 at 12:34 PM, Jim Hargreaves wrote: > Dear List, > > I have a list of length ~1000 filled with numerics. I need to replace the > elements of this list that are above a certain numerical threshold with the > value of the threshold. > > e.g > example=list(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1) > threshold=5 > > example=(1, 2, 3, 4, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 4, 3, 2, 1). > > I have written a crude script that achieves this but it's very slow. Is > there a way to do this using some R function? > > Crude script: http://pastebin.com/3KSfi8nD > > __ > 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. > -- Joris Meys Statistical consultant Ghent University Faculty of Bioscience Engineering Department of Applied mathematics, biometrics and process control tel : +32 9 264 59 87 joris.m...@ugent.be --- Disclaimer : http://helpdesk.ugent.be/e-maildisclaimer.php __ 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.
