[R] plotting polynomial regression line

[Uwe Ligges]

On 20.12.2009 19:35, Amit wrote:
> Dear All,
> I am trying to plot polynomial regression line to a scatterplot. I did
> following so far:
>
>> x=c(1:9335)
>> y=read.table("gp.txt",header=T,sep="\t")
>> length(y$PCC) # y$PCC has values between 1 to 0 in decreasing order
> [1] 9335
>> plot(x,y$PCC,col="red") #scatterplot between x and y$PCC
>> reg=lm(y$PCC~poly(x,6)) # calculating polynomial fit with degree 6
>> abline(reg,col="blue")
> Warning message:
> In abline(reg, col = "blue") :
>    only using the first two of 7regression coefficients


abline() draws straight lines.


> After the above warning a line is drawn in the graph parallel to the
> y-axis. But I was expecting a curve line through the scatterplot.
> Am I doing something wrong? Please help!


You can predict() some points along your x values and connect them via 
lines().

Best wishes,
Uwe Ligges



> Best
> Amit
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.