TsparseMatrix-class {Matrix} | R Documentation |
The "TsparseMatrix"
class is the virtual class of
all sparse matrices coded in triplet form. Since it is a virtual class,
no objects may be created from it. See
showClass("TsparseMatrix")
for its subclasses.
Dim
, Dimnames
:from the "Matrix"
class,
i
:Object of class "integer"
- the row indices
of non-zero entries in 0-base, i.e., must be in
0:(nrow(.)-1)
.
j
:Object of class "integer"
- the column
indices of non-zero entries. Must be the same length as slot
i
and 0-based as well, i.e., in
0:(ncol(.)-1)
. For numeric Tsparse matrices, (i,j)
pairs can occur more than once, see dgTMatrix
.
Class "sparseMatrix"
, directly.
Class "Matrix"
, by class "sparseMatrix"
.
Extraction ("["
) methods, see
[-methods
.
Most operations with sparse matrices are performed using the
compressed, column-oriented or CsparseMatrix
representation. The triplet representation is convenient for
creating a sparse matrix or for reading and writing such
matrices. Once it is created, however, the matrix is generally
coerced to a CsparseMatrix
for further
operations.
Note that all new(.)
, spMatrix
and
sparseMatrix(*, giveCsparse=FALSE)
constructors
for "TsparseMatrix"
classes implicitly add x_k's that belong to identical
(i_k, j_k) pairs, see, the example below, or also
"dgTMatrix"
.
For convenience, methods for some operations such as %*%
and crossprod
are defined for
TsparseMatrix
objects. These methods simply
coerce the TsparseMatrix
object to a
CsparseMatrix
object then perform the
operation.
its superclass, sparseMatrix
, and the
dgTMatrix
class, for the links to other classes.
showClass("TsparseMatrix") ## or just the subclasses' names names(getClass("TsparseMatrix")@subclasses) T3 <- spMatrix(3,4, i=c(1,3:1), j=c(2,4:2), x=1:4) T3 # only 3 non-zero entries, 5 = 1+4 !