[R] question about matrix
Thomas W Blackwell
tblackw at umich.edu
Wed Nov 12 20:36:22 CET 2003
Mikyoung -
All answers are "yes", but IMHO you are trying to be
too clever with your data structure. Programming is
*much* easier if you keep things simple.
Specifically:
(1) The function matrix() will happily build you
a matrix of type "list", with each element of the list
occupying one cell in the matrix. For example,
tma <- matrix(as.list(letters), nrow=13, ncol=2)
is.list(tma)
[1] TRUE
is.matrix(tma)
[1] TRUE
tma[5,2]
[[1]]
[1] "r"
Same effect with
tma <- as.list(letters)
dim(tma) <- c(13,2)
(2) Complex numbers - see help("complex"). This
help page even gives an example which constructs a
matrix of complex numbers.
(3) To find the rank of matrix x, qr(x)$rank.
I don't think there is a specific extractor function
for this component, but I could be wrong.
(4) But, once again, I think you would be better served by
storing your two values of different types either as two
separate matrices, or as two columns in a data frame, with
additional columns of repetitive integers to indicate the
row and column in your conceptual matrix.
See help("tapply"), help("aggregate") for two functions
which can operate on such a data structure, and help("gl")
help("col"), help("row") for functions that will generate
the additional columns.
HTH - tom blackwell - u michigan medical school - ann arbor -
On Wed, 12 Nov 2003, Mikyoung Jun wrote:
> Hello,
>
> I have a few questions about matrix in R.
>
> Can we make a matrix whose elements are list? I would like to save two
> different values in each elements of matrix. If there is a package or
> something which can deal with complex numbers, that will do it too. Also,
> I am wondering whether there is a function to calculate the rank of the
> matrix. I found a matrix package, but it doesn't have functions like that.
>
> Thanks a lot in advance!
>
> Mikyoung Jun
>
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