[R] natural cubic splines

[David Winsemius]

On May 4, 2011, at 8:34 AM, Joshua Wiley wrote:

> Hi Ondrej,
>
> What documentation have you looked at?  Does this help at all?
>
> require(splines)
> ?ns
> ## one example
> summary(lm(y ~ ns(x, df = 3),
>  data = data.frame(y = runif(100), x = rbinom(100, 9, .25)^2)))
>
> ## built in examples
> example(ns)
>
> Also, I am very fond of the book, Modern Applied Statistics with S by
> Venables & Ripley.  It has a section on splines that might help you.
>

Agree on that last point entirely. I understand that restricted cubic  
splines are another name for natural splines (but would welcome  
correction if that understanding is in error). They are used  
extensively in the rms/Hmisc package combination with the supporting  
text "Regression Modeling Strategies".

-- 
David
> Cheers,
>
> Josh
>
>
> 2011/5/4 Ondřej Mikula <onmikula at gmail.com>:
>> Dear R-helpers,
>> I need to fit natural cubic spline with specified number of knots. I
>> expected 'splines' package will be helpful, but I am confused by its
>> help. Is more detailed documentation available for it or could you
>> recommend another R function?
>> Best regards
>> Ondrej Mikuladucible code.
>>
>

David Winsemius, MD
Heritage Laboratories
West Hartford, CT