[R] 2 simple doubts

Adaikalavan Ramasamy ramasamy at stats.ox.ac.uk
Wed Jul 10 12:23:13 CEST 2002

> 1) I couldn't discover what is the command for a concatenation of 2
> variable strings.

You can use c, cbind, rbind. Example follow :
x <- c(1,2,46) which returns you a vector of length 3 containing the number
1,2, 4
if you have a numerical matrix of say  X, Y, Z each of dim 10 by 2
    then A <- cbind(X,Y,Z) binds the colums together to give a matrix of 10
by 6
    or    B <- rbind( X,Y,Z) binds the rows together to give a matrix of 30
by 2

If some of your vectors are non-numerical, then you may have to use the
data.frame option instead.

> 2) For example, if I have three variable strings, and each one has the
> name of a variable in a data matrix:
> a<-V1
> b<-V2
> c<-V3
> , is it possible to construct a command like this:
> tree(a~b+c,data=DS1)
> , that would do the job of tree(V1~V2+V3,data=DS1) ?

Hmm, I am not quite sure what you are asking but you best try with a small
manage matrix first.
I think you are trying the change the names of your columns right ? If so
try this

colnames(DS1) <- c( "a", "b", "c")

Note the quotes around a,b, c. Thus you need not to extract each vector by
its own.
Again for dataframes, the naming procedure is slightly different. refer to

Regards, Adai.

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