[R] Help on Dates in R again

[Thorsten Muehge]

Hello R Experts,
I want to aggregate parameters by week. But our production week ends Friday
night instead of Sunday Night which is the default value in R.

In order to solve the problem I want to substract two days from the current
data and than use the R function

test$week<-format(test$dates,"%U");

with a test&dates format equal to "2006-09-21".

How do I substract the two days from the test$dates column in the
data.frame?

Thanks a lot for your help
Thorsten