[R] Cubic B-spline, how to numerically integrate?
dwinsemius at comcast.net
Fri May 14 18:36:26 CEST 2010
On May 14, 2010, at 11:57 AM, David Winsemius wrote:
> On May 14, 2010, at 11:41 AM, Claudia Penaloza wrote:
>> (corrected version of previous posting)
>> I fit a GAM to turtle growth data following methods in Limpus &
>> 1997 (http://www.int-res.com/articles/meps/149/m149p023.pdf).
>> I want to obtain figures similar to Fig 3 c & f in Limpus & Chaloupka
>> (1997), which according to the figure legend are "expected size-at-
>> functions" obtained by numerically integrating "size-specific
>> growth rate
>> functions derived using cubic B-spline fit to GAM predicted values".
>> I was able to fit the cubic-B spline, but I do not know how to
>> integrate" it.
> You need to give us the function and the appropriate limits of
Maybe it is even easier than I thought. Assuming your interest lies
with the last fitted line ... the one on the third page ... you could
perhaps just see how successful this strategy would be:
# Presumably you have already done:
Int.fit <- seq(100, 600, by=0.1)*predict(bspline3,
by=0.1) ) )
You would need to do a sensibility check by comparing the result to a
back of the envelope estimate: say 55*500=27500 . I'm a bit concerned
that a dimensional analysis suggest this is an estimate of mm^2/yr,
although I suppose a yearly surface area increase could be a
meaningful value in some domain or another
>> Can anybody help please?
>> Code and figures here:
>> Thank you,
> David Winsemius, MD
> West Hartford, CT
> R-help at r-project.org mailing list
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
David Winsemius, MD
West Hartford, CT
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