| symmetricMatrix-class {Matrix} | R Documentation |
The virtual class of symmetric matrices, "symmetricMatrix",
from the package Matrix contains numeric and logical, dense and
sparse matrices, e.g., see the examples.
The main use is in methods (and C functions) that can deal with all symmetric matrices.
uplo:Object of class "character". Must be
either "U", for upper triangular, and "L", for lower triangular.
Dim, Dimnames:The dimension (a length-2
"integer") and corresponding names (or NULL),
inherited from the Matrix, see there. See below,
about storing only one of the two Dimnames components.
factors:a list of matrix factorizations, also from the
Matrix class.
Class "Matrix", directly.
signature(from = "ddiMatrix", to =
"symmetricMatrix"): and many other coercion methods, some of
which are particularly optimized.
signature(object = "symmetricMatrix"):
returns symmetric dimnames, even when the
Dimnames slot only has row or column names. This allows to
save storage for large (typically sparse) symmetric matrices.
signature(object = "symmetricMatrix"):
returns TRUE trivially.
There's a C function symmetricMatrix_validate()
called by the internal validity checking functions, and also from
getValidity(getClass("symmetricMatrix")).
dimnamesThe validity checks do not require a symmetric Dimnames slot,
so it can be list(NULL, <character>), e.g., for efficiency.
However, dimnames() and other functions and methods
should behave as if the dimnames were symmetric, i.e., with both list
components identical.
isSymmetric which has efficient methods
(isSymmetric-methods) for the Matrix classes.
Classes triangularMatrix, and, e.g.,
dsyMatrix for numeric dense matrices, or
lsCMatrix for a logical sparse matrix class.
## An example about the symmetric Dimnames:
sy <- sparseMatrix(i= c(2,4,3:5), j= c(4,7:5,5), x = 1:5, dims = c(7,7),
symmetric=TRUE, dimnames = list(NULL, letters[1:7]))
sy # shows symmetrical dimnames
sy@Dimnames # internally only one part is stored
dimnames(sy) # both parts - as sy *is* symmetrical
showClass("symmetricMatrix")
## The names of direct subclasses:
scl <- getClass("symmetricMatrix")@subclasses
directly <- sapply(lapply(scl, slot, "by"), length) == 0
names(scl)[directly]
## Methods -- applicaple to all subclasses above:
showMethods(classes = "symmetricMatrix")