[R] Fitting Richards' curve

[Bernard Comcast]

I have been using nlsr() to fit s curves to Covid-19 data over the past few weeks and I have not had any issues.

Bernard
Sent from my iPhone so please excuse the spelling!"

> On May 13, 2020, at 5:16 PM, Abby Spurdle <spurdle.a using gmail.com> wrote:
> 
> Hi Christofer,
> 
> This doesn't really answer your question.
> But if the goal is to fit an S-shaped curve to data, with increased
> flexibility...
> (I'm assuming that's the goal).
> 
> ...then I'd like to note the option of splines (or smoothing), subject
> to shape constraints...
> 
> My guess, is it's probably easier to model the inverse of a growth
> curve this way, than to model the growth curve directly.
> In which case, a 4-piece to 10-piece spline should give considerably flexibly.
> 
> It's possible that Martin's package, cobs, can do this, but not sure,
> I haven't tried it.
> And there may be other R packages for fitting splines/smoothers to
> data, subject to shape constraints.
> 
> If not, I'm guessing it wouldn't be too difficult to implement, via
> extensions to the quadprog package, for quadratic programming.
> 
> 
>> On Wed, May 13, 2020 at 9:26 PM Christofer Bogaso
>> <bogaso.christofer using gmail.com> wrote:
>> 
>> Hi,
>> 
>> Is there any R package to fit Richards' curve in the form of
>> https://en.wikipedia.org/wiki/Generalised_logistic_function
>> 
>> I found there is one package grofit, but currently defunct.
>> 
>> Any pointer appreciated.
>> 
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> 
> ______________________________________________
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> and provide commented, minimal, self-contained, reproducible code.