# lines.spm: Add a curves to an existing plot. In SemiPar: Semiparametic Regression

## Description

Takes a fitted `spm` object produced by `spm()` and adds a curve. The function is only appropriate in the case of a single predictor.

## Usage

 ```1 2``` ```## S3 method for class 'spm' lines(x,...) ```

## Arguments

 `x` a fitted `spm` object as produced by `spm()`. `...` other graphics parameters described in Appendix B of the SemiPar Users' Manual http:uow.edu.au/~mwand/SPmanu.pdf

## Details

Takes a fitted `spm` object produced by `spm()` and adds a curve. The function is only appropriate in the case of a single predictor.

## Value

The function adds a curve to a plot.

## Author(s)

M.P. Wand [email protected] (other contributors listed in SemiPar Users' Manual).

## References

Ruppert, D., Wand, M.P. and Carroll, R.J. (2003)
Semiparametric Regression Cambridge University Press.
http://stat.tamu.edu/~carroll/semiregbook/

Ganguli, B. and Wand, M.P. (2005)
SemiPar 1.0 Users' Manual.
http://www.uow.edu.au/~mwand/SPmanu.pdf

`spm` `plot.spm` `predict.spm` `summary.spm` `residuals.spm` `fitted.spm`
 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16``` ```library(SemiPar) data(fossil) attach(fossil) fit <- spm(strontium.ratio~f(age)) plot(fossil,type="n") lines(fit) points(fossil) # Now do several customisations op <- par(bg="white") par(bg="honeydew") plot(fossil,type="n") lines(fit,col="green",lwd=5,shade.col="mediumpurple1") points(fossil,col="orange",pch=16) par(op) ```