[R] automate curve drawing on nls() object

Ben Bolker bolker at ufl.edu
Wed May 19 01:33:20 CEST 2010

array chip <arrayprofile <at> yahoo.com> writes:

> Hi, I would like to use the curve() function to draw the 
> predicted curve from an nls() object. for example:

  Is there a reason you don't want to use plot() and predict() ???
> dd<-read.table("dd.txt",sep='\t',header=T,row.names=1)

  note that this is not a reproducible example ...

> obj<-nls(y~c+(d-c)/(1+(x/e)^b),data=dd,start=list(b=-1, c=0, d=100, e=150))
> coef(obj)
>           b           c           d           e 
>  -1.1416422   0.6987028 102.8613176 135.9373131
> curve(0.699+(102.86-0.699)/(1+(x/135.94)^(-1.1416)),1,20000)

  predframe <- data.frame(x=seq(1,20000,length.out=101))
  predframe <- cbind(predframe,y=predict(obj,newdata=predframe))

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