R help - Aug 2007 - How to store the parameter estimated by nls( ) to a variable?

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!

Best Wishes

Yuchen Luo

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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