[R] Matrix/Data.Frame questions

Thomas Lumley tlumley at u.washington.edu
Tue Oct 30 18:04:13 CET 2001

On Tue, 30 Oct 2001, Laura Gross wrote:

> Dear list
> Thanks to all who answered my query yesterday regarding the maximum size
> of a matrix in R.
> I have a couple more questions to ask with being new to R!
> 1. Having imported my data into R from SPSS, I have a data.frame
> consisting of several variables. I am wanting to store my response
> variable, Y, and four explanatory variables, X, in vectors/matrices. How
> can I do this in R?

I don't think you really do want to do this, but if you do, and your
dataframe is called df, with columns called Y, X1,X2,X3,X4


You could also do
and then the columns of the data frame would behave like separate
variables called Y, X1,...,X4.

A lot of the modelling and some of the graphics functions in R are
designed to work on data frames, so it's usually easier to keep your data
frame together rather than separating out the variables.

> 2. If I have say a 4x4 matrix, A, and I want to extract part of this
> matrix to create a submatrix, B, (say row 1:3 and column 1:3) how can I
> do this?
> Could it be done something like: B<-A[1:3,1:3] ?

Yes, exactly.


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