Re: [R] Finding a scalar value...
Your best option is to read the relevant help files. A simple (untested) example to find R when P, T and scal.fn=Z is given, is to do this: my.fun <- function(P, R, T, Z) scal.fn(P, R, T) - Z uniroot( fn, R=rr, T=tt, Z=zz, lower=-100, upper=100 )$root You have to make an intelligent guess on the upper and lower ranges for the parameter R. I have used +/- 1 million as a silly example. HOWEVER, I do not think this works when P,R,T,Z are scalars. Try it to be sure. If not, then you may have to write a for or apply loop. Regards, Adai On 16/08/2010 13:19, Petar Milin wrote: Thanks for the answer! However, if I would have scal.fn() like below, how would I apply uniroot() or optimize() or the like? Best, PM On 16/08/10 13:24, Adaikalavan Ramasamy wrote: You probably need to look up on how to write functions. Try scal.fn<- function(P, R, T){ out<- ( 1/R - T ) / ( P - T ) return(out) } Here is a fake example: df<- cbind.data.frame( P=rnorm(10), R=rnorm(10), T=rnorm(10) ) scal.fn( df$P, df$R, df$T ) Or are you trying to solve other parameters given scal values? If so, try having a look at functions like uniroot(). Regards, Adai On 16/08/2010 11:48, Petar Milin wrote: Hello! I need to find a simple scalar value: Scal = ((1/R) - T) / (P - T), where R, T, and P are vectors in a data.frame. Please, can anyone tell me how to solve that in R? Best, PM __ 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] Finding a scalar value...
Thanks for the answer! However, if I would have scal.fn() like below, how would I apply uniroot() or optimize() or the like? Best, PM On 16/08/10 13:24, Adaikalavan Ramasamy wrote: You probably need to look up on how to write functions. Try scal.fn <- function(P, R, T){ out <- ( 1/R - T ) / ( P - T ) return(out) } Here is a fake example: df <- cbind.data.frame( P=rnorm(10), R=rnorm(10), T=rnorm(10) ) scal.fn( df$P, df$R, df$T ) Or are you trying to solve other parameters given scal values? If so, try having a look at functions like uniroot(). Regards, Adai On 16/08/2010 11:48, Petar Milin wrote: Hello! I need to find a simple scalar value: Scal = ((1/R) - T) / (P - T), where R, T, and P are vectors in a data.frame. Please, can anyone tell me how to solve that in R? Best, PM __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
Re: [R] Finding a scalar value...
You probably need to look up on how to write functions. Try scal.fn <- function(P, R, T){ out <- ( 1/R - T ) / ( P - T ) return(out) } Here is a fake example: df <- cbind.data.frame( P=rnorm(10), R=rnorm(10), T=rnorm(10) ) scal.fn( df$P, df$R, df$T ) Or are you trying to solve other parameters given scal values? If so, try having a look at functions like uniroot(). Regards, Adai On 16/08/2010 11:48, Petar Milin wrote: Hello! I need to find a simple scalar value: Scal = ((1/R) - T) / (P - T), where R, T, and P are vectors in a data.frame. Please, can anyone tell me how to solve that in R? Best, PM __ 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.
[R] Finding a scalar value...
Hello! I need to find a simple scalar value: Scal = ((1/R) - T) / (P - T), where R, T, and P are vectors in a data.frame. Please, can anyone tell me how to solve that in R? Best, PM __ 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.