[R] Simplest question ever...
Let's say i have a = c(1, 4, 5) b = c(2, 6, 7) and i have matrix m, what's an efficient way of access m[1, 2], m[4, 6], m[5, 7] like of course m[a, b] = is not going to do, but what's an expression that will allow me to have that list? Thanks! -- View this message in context: http://www.nabble.com/Simplest-question-ever...-tf3329894.html#a9258932 Sent from the R help mailing list archive at Nabble.com. __ R-help@stat.math.ethz.ch 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] Simplest question ever...
I'm not sure this is the most efficient, but how about: diag(m[a,b]) ? On 3/1/07, yoo <[EMAIL PROTECTED]> wrote: > > Let's say i have > > a = c(1, 4, 5) > b = c(2, 6, 7) > > and i have matrix m, what's an efficient way of access > m[1, 2], m[4, 6], m[5, 7] > like of course m[a, b] = is not going to do, but what's an expression that > will allow me to have that list? > > Thanks! > -- > View this message in context: > http://www.nabble.com/Simplest-question-ever...-tf3329894.html#a9258932 > Sent from the R help mailing list archive at Nabble.com. > > __ > R-help@stat.math.ethz.ch 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@stat.math.ethz.ch 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] Simplest question ever...
try: > a = c(1, 4, 5) > b = c(2, 6, 7) > > m <- matrix(1:49,7,7) > m[cbind(a,b)] # 'array' indexing [1] 8 39 47 > m [,1] [,2] [,3] [,4] [,5] [,6] [,7] [1,]18 15 22 29 36 43 [2,]29 16 23 30 37 44 [3,]3 10 17 24 31 38 45 [4,]4 11 18 25 32 39 46 [5,]5 12 19 26 33 40 47 [6,]6 13 20 27 34 41 48 [7,]7 14 21 28 35 42 49 > Jim Holtman "What is the problem you are trying to solve?" - Original Message From: yoo <[EMAIL PROTECTED]> To: r-help@stat.math.ethz.ch Sent: Thursday, March 1, 2007 4:28:02 PM Subject: [R] Simplest question ever... Let's say i have a = c(1, 4, 5) b = c(2, 6, 7) and i have matrix m, what's an efficient way of access m[1, 2], m[4, 6], m[5, 7] like of course m[a, b] = is not going to do, but what's an expression that will allow me to have that list? Thanks! -- View this message in context: http://www.nabble.com/Simplest-question-ever...-tf3329894.html#a9258932 Sent from the R help mailing list archive at Nabble.com. __ R-help@stat.math.ethz.ch 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. Access over 1 million songs. [[alternative HTML version deleted]] __ R-help@stat.math.ethz.ch 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] Simplest question ever...
On 01-Mar-07 Paul Lynch wrote: > I'm not sure this is the most efficient, but how about: >diag(m[a,b]) > ? m[cbind(a,b)] will also do it: m [,1] [,2] [,3] [,4] [,5] [,6] [,7] [1,] 1.1 1.2 1.3 1.4 1.5 1.6 1.7 [2,] 2.1 2.2 2.3 2.4 2.5 2.6 2.7 [3,] 3.1 3.2 3.3 3.4 3.5 3.6 3.7 [4,] 4.1 4.2 4.3 4.4 4.5 4.6 4.7 [5,] 5.1 5.2 5.3 5.4 5.5 5.6 5.7 a <- c(1, 4, 5) b <- c(2, 6, 7) diag(m[a,b]) [1] 1.2 4.6 5.7 m[cbind(a,b)] [1] 1.2 4.6 5.7 Ted. > On 3/1/07, yoo <[EMAIL PROTECTED]> wrote: >> >> Let's say i have >> >> a = c(1, 4, 5) >> b = c(2, 6, 7) >> >> and i have matrix m, what's an efficient way of access >> m[1, 2], m[4, 6], m[5, 7] >> like of course m[a, b] = is not going to do, but what's an expression >> that >> will allow me to have that list? >> >> Thanks! >> -- >> View this message in context: >> http://www.nabble.com/Simplest-question-ever...-tf3329894.html#a9258932 >> Sent from the R help mailing list archive at Nabble.com. >> >> __ >> R-help@stat.math.ethz.ch 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@stat.math.ethz.ch 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. E-Mail: (Ted Harding) <[EMAIL PROTECTED]> Fax-to-email: +44 (0)870 094 0861 Date: 01-Mar-07 Time: 23:44:22 -- XFMail -- __ R-help@stat.math.ethz.ch 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] Simplest question ever...
If I understand it correctly, you mean to say >a = c(1, 4, 5) >b = c(2, 6, 7) and m<- rbind(a,b) if you want to see a particular column you can try m[,1] hope it helps, -GS On 3/2/07, yoo <[EMAIL PROTECTED]> wrote: > > > Let's say i have > > a = c(1, 4, 5) > b = c(2, 6, 7) > > and i have matrix m, what's an efficient way of access > m[1, 2], m[4, 6], m[5, 7] > like of course m[a, b] = is not going to do, but what's an expression that > will allow me to have that list? > > Thanks! > -- > View this message in context: > http://www.nabble.com/Simplest-question-ever...-tf3329894.html#a9258932 > Sent from the R help mailing list archive at Nabble.com. > > __ > R-help@stat.math.ethz.ch 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@stat.math.ethz.ch 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.
