[R] spline interpolation

David Winsemius dwinsemius at comcast.net
Sat Feb 5 16:24:04 CET 2011


On Feb 5, 2011, at 9:29 AM, Asan Ramzan wrote:

> Hello R-help
> I have the following data for a standard curve
> concentration(nM),fluorescence
> 0,48.34
> 2,58.69
> 5,70.83
> 10,94.73
> 20,190.8
> 50,436.0
> 100, 957.9
>
> (1)Is there function in R to plot a spline.

?spline

> (2)How can I interpolation,say 1000 point from 0nM-100nM and store  
> this as a
> data frame of concentration,fluorescence

?approxfun

> (3)How can I modify the code below so that instead of retrieving a  
> concentration
> with the exact value of fluorescence, it gives me concentration for  
> the value
> that is closest to that fluorescence.

?which.min  #(although I would be using "[" rather than subset for  
that purpose.)

>
> subset(df,fluorescence==200.3456,select=concentration)
>
>
>
> 	[[alternative HTML version deleted]]
>
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David Winsemius, MD
West Hartford, CT



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