[R] How to store the parameter estimated by nls( ) to a variable?

Duncan Murdoch murdoch at stats.uwo.ca
Sun Aug 12 14:26:29 CEST 2007

Yuchen Luo wrote:
> Dear Colleagues.
> I believe this should be a problem encountered by many:
> nls( ) is a very useful and efficient function to use if we are just to
> display the estimated value on screen. What if we need R to store the
> estimated parameter in a variable?
> For example:
> x=rnorm(10, mean=1000, sd=10)
> y=x^2+100+rnorm(10)
> a=nls(y~(x^2+para),control=list(maxiter = 1000, minFactor=0.5
> ^1024),start=list(para=0.0))
> How to store the estimated value of para in this case, in a variable, say,
> b?
> It is easy to display a and find all the information. How ever, I need to
> fit a different set of x and y in every loop of my code and I need to store
> the estimated values for further use. I have checked both the online manual
> and several S-plus books but no example as such showed up.
> Your help will be highly appreciated!

coef(a) will get what you want.  coef() works for most modelling 
functions where it makes sense.

Duncan Murdoch

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