I think that a pointer to ?formula needs to be added to ?":"
On 1/31/06, Liaw, Andy <[EMAIL PROTECTED]> wrote: > ":" in a formula is not the same as ":" otherwise! > > Andy > > From: Ionut Florescu > > > > a:b means - all the element in the vector from a to b > > a[,-1] means for the matrix a keep all the rows but not the last or > > first -can't remember column. > > When in doubt do what I do make a small matrix and apply the > > command see > > what it does. > > After this: > > > a=matrix(c(1:9),3,3) > > > a[,-1] > > [,1] [,2] > > [1,] 4 7 > > [2,] 5 8 > > [3,] 6 9 > > > > you see that -1 eliminates the first column. > > I found the R manual useless myself. > > The only thing useful is the search function in the html > > help. That has > > examples. > > > > Ionut Florescu > > > > Michael wrote: > > > 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! > > > > > > [[alternative HTML version deleted]] > > > > > > ______________________________________________ > > > R-help@stat.math.ethz.ch mailing list > > > https://stat.ethz.ch/mailman/listinfo/r-help > > > PLEASE do read the posting guide! > > http://www.R-project.org/posting-guide.html > > > > > > > > > > ______________________________________________ > > R-help@stat.math.ethz.ch mailing list > > https://stat.ethz.ch/mailman/listinfo/r-help > > PLEASE do read the posting guide! > > http://www.R-project.org/posting-guide.html > > > > > > ______________________________________________ > R-help@stat.math.ethz.ch mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html > ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
