need suggestion about building formual
Thanks for your kind respond. Although the answer didn't solve my question clearly,maybe I still not understand the art of R. I'm sorry that I had not talked the problem clearly, maybe a example with more detail will be suitable as suggested in the the posting guide. In function fitting program, such as Sigmaplot, a fitting formula, can be write in separate form: G=a+(b*x)^(1/2) k=exp((G-G0)/(R*T)) fit k to y of course,in R's nls, can write as: mynls<-nls(formula=y~exp((a+(b*x)^(1/2)-G0)/(R*T)),data=mydata,...) In this example, the formula is simple and acceptable. However, when the formula is more complexity,writing all in one formula,the readability will be damaged.So I'm looking for a way to write simple and readable code in this situation.
Spencer Graves wrote:
I'm not certain what you are asking.
You can build expressions in R as character strings and then execute
them. Example:
expr <- paste("two <-", 1, "+", 1)
eval(parse(text=expr))
two
If this does not answer your question, PLEASE do read the posting
guide, "www.R-project.org/posting-guide.html". It can help increase the
chances of a quick and useful reply.
spencer graves
Simple wrote:
hi, I'm an newbie for R,I want do some fitting in R. I wander if it is possible to write a few of equations but only one formual when fitting Currently,My problem is,in R, is there methods combination a few equations into one formual? For example, y=f1(k); k=f2(t); t=f3(x); although it is certain that the can be equations turn into one formual as y~f(x),but write such a complexity string make me painful. I have searched the web and found out there were only examples with one formual.any suggestion? I hope that I have omit something.