Re: [R] Help! What does this R command mean?

From: Ionut Florescu <ifloresc_at_stevens.edu>
Date: Wed 01 Feb 2006 - 08:09:54 EST

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 Received on Wed Feb 01 08:35:21 2006

This archive was generated by hypermail 2.1.8 : Wed 01 Feb 2006 - 14:16:50 EST