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Error in using by in R

I'm new to R and started using it to implement a gam model. I've been following this tutorial examples and R keeps throwing an error when I try to use by. I really have no idea what's wrong and would appreciate it if anybody can suggest something.

Thanks a lot in advance.

    >require(mgcv)
    >set.seed(10)
    ## simulate date from y = f(x2)*x1 + error
    >dat <- gamSim(3,n=400)
    Continuous `by' variable example
    >b<-gam(y ~ s(x2,by=x1),data=dat)
    Error in s(x2, by = x1) : unused argument (by = x1)

enter image description here

Additional information: R version = 3.3.1 (2013-06-21) OS = Windows 10

Solution

  • Code

    require(mgcv)
set.seed(10)
## simulate date from y = f(x2)*x1 + error
dat <- gamSim(3,n=400)

b <- gam(y ~ s(x2,by=x1),data=dat)
b

    Result

    Continuous `by' variable example

    Family: gaussian Link function: identity

    Formula: y ~ s(x2, by = x1)

    Estimated degrees of freedom: 9.2 total = 10.2

    GCV score: 4.518245

    Please start a fresh R session and see if you get the same error. Also, please check your version of mgcv and make sure it's up to date.