[R] update.formula drop interaction terms

Dieter Menne dieter.menne at menne-biomed.de
Wed Oct 14 08:53:43 CEST 2009

Eleni Rapsomaniki-2 wrote:
> How do I drop multiplication terms from a formula using update?
> e.g.
> forml=as.formula("Surv(time, status) ~ x1+x2+A*x3+A*x4+B*x5+strata(sex)")

The easiest way is to write the formula again without the A's. 


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