Bert, I guess I could have been a little more authoritative: the code unique(a[sapply(b,function(x) which.min(abs(x-a)))]) is exactly what I need. Thanks for the input, your comments helped us make the code better,
Andras --- On Tue, 6/18/13, Bert Gunter <gunter.ber...@gene.com> wrote: > From: Bert Gunter <gunter.ber...@gene.com> > Subject: Re: [R] find closest value in a vector based on another vector values > To: "Andras Farkas" <motyoc...@yahoo.com> > Cc: "Jorge I Velez" <jorgeivanve...@gmail.com>, "R mailing list" > <r-help@r-project.org> > Date: Tuesday, June 18, 2013, 10:55 AM > Andras: > > No. > Using the a = c(1,8,9) and b = 2:3 that ** I posted > before**, you get > the single unique value of 1. > > Please stop guessing, think carefully about what you want to > do, and > **test** your code. > > -- Bert > > On Tue, Jun 18, 2013 at 7:41 AM, Andras Farkas <motyoc...@yahoo.com> > wrote: > > Bert, > > > > thanks... The values should not repeat themselves if > the same a is closest to all b, so probably aruns example > extended with a unique command works best? > > > > unique(a[sapply(b,function(x) which.min(abs(x-a)))]) > > > > thanks, > > > > Andras > > > > --- On Tue, 6/18/13, Bert Gunter <gunter.ber...@gene.com> > wrote: > > > >> From: Bert Gunter <gunter.ber...@gene.com> > >> Subject: Re: [R] find closest value in a vector > based on another vector values > >> To: "Jorge I Velez" <jorgeivanve...@gmail.com> > >> Cc: "Andras Farkas" <motyoc...@yahoo.com>, > "R mailing list" <r-help@r-project.org> > >> Date: Tuesday, June 18, 2013, 10:07 AM > >> Jorge: No. > >> > >> > a <-c(1,5,8,15,32,33.5,69) > >> > b <-c(8.5,33) > >> > a[findInterval(b, a)] > >> [1] 8 32 ##should be > >> 8 33.5 > >> > >> I believe it has to be done explicitly by finding > all the > >> differences > >> and choosing those n with minimum values, depending > on what > >> n you > >> want. > >> > >> Note that the problem is incompletely specified. > What if the > >> same > >> value of a is closest to several values of b? -- do > you want > >> all the > >> values you choose to be different or not, in which > case they > >> may not > >> be minimum? > >> > >> a <- c(1, 8, 9) > >> b <- c(2,3) > >> > >> Then what are the 2 closest values of a to b? > >> > >> -- Bert > >> > >> On Tue, Jun 18, 2013 at 5:43 AM, Jorge I Velez > <jorgeivanve...@gmail.com> > >> wrote: > >> > Dear Andras, > >> > > >> > Try > >> > > >> >> a[findInterval(b, a)] > >> > [1] 8 32 > >> > > >> > HTH, > >> > Jorge.- > >> > > >> > > >> > On Tue, Jun 18, 2013 at 10:34 PM, Andras > Farkas <motyoc...@yahoo.com> > >> wrote: > >> > > >> >> Dear All, > >> >> > >> >> would you please provide your thoughts on > the > >> following: > >> >> let us say I have: > >> >> > >> >> a <-c(1,5,8,15,32,69) > >> >> b <-c(8.5,33) > >> >> > >> >> and I would like to extract from "a" the > two values > >> that are closest to > >> >> the values in "b", where the length of > this vectors > >> may change but b will > >> >> allways be shorter than "a". So at the end > based on > >> this example I should > >> >> have the result "f" as > >> >> > >> >> f <-c(8,32) > >> >> > >> >> appreciate the help, > >> >> > >> >> Andras > >> >> > >> >> > ______________________________________________ > >> >> 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. > >> >> > >> > > >> > > [[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. > >> > >> > >> > >> -- > >> > >> Bert Gunter > >> Genentech Nonclinical Biostatistics > >> > >> Internal Contact Info: > >> Phone: 467-7374 > >> Website: > >> http://pharmadevelopment.roche.com/index/pdb/pdb-functional-groups/pdb-biostatistics/pdb-ncb-home.htm > >> > > > > -- > > Bert Gunter > Genentech Nonclinical Biostatistics > > Internal Contact Info: > Phone: 467-7374 > Website: > http://pharmadevelopment.roche.com/index/pdb/pdb-functional-groups/pdb-biostatistics/pdb-ncb-home.htm > ______________________________________________ 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.
