Hi all,

R is so difficult. I am so desperate.

What does the ":" mean in the following statement?

What does the "[, -1]" mean?

>
> # Leaps takes a design matrix as argument: throw away the intercept
> # column or leaps will complain
>
> X <- model.matrix(lm(V ~ I + D + W +G:I + P + N, election.table))[,-1]

Thanks a lot!

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