lsparseMatrix-classes {Matrix} | R Documentation |
The lsparseMatrix
class is a virtual class of sparse
matrices with TRUE
/FALSE
entries. Only the positions of the
elements that are TRUE
are stored. These can be stored in the
``triplet'' form (classes lgTMatrix
, lsTMatrix
, and
ltTMatrix
which really contain pairs, not triplets) or in
compressed column-oriented form (classes lgCMatrix
, lsCMatrix
, and
ltCMatrix
) or in compressed row-oriented form (classes lgRMatrix
, lsRMatrix
, and
ltRMatrix
). The second
letter in the name of these non-virtual classes indicates
g
eneral, s
ymmetric, or t
riangular.
Objects can be created by calls of the form new("lgCMatrix",
...)
and so on. More frequently objects are created by coercion of
a numeric sparse matrix to the logical form for use in
the symbolic analysis phase
of an algorithm involving sparse matrices. Such algorithms often
involve two phases: a symbolic phase wherein the positions of the
non-zeros in the result are determined and a numeric phase wherein the
actual results are calculated. During the symbolic phase only the
positions of the non-zero elements in any operands are of interest,
hence any numeric sparse matrices can be treated as logical sparse
matrices.
uplo
:"character"
. Must be
either "U", for upper triangular, and "L", for lower
triangular. Present in the triangular and symmetric classes but not
in the general class.diag
:"character"
. Must be
either "U"
, for unit triangular (diagonal is all ones), or
"N"
for non-unit. The implicit diagonal elements are not
explicitly stored when diag
is "U"
. Present in the
triangular classes only.p
:"integer"
of pointers, one
for each column (row), to the initial (zero-based) index of elements in
the column. Present in compressed column-oriented and compressed
row-oriented forms only.i
:"integer"
of length nnzero
(number of non-zero elements). These are the row numbers for
each TRUE element in the matrix. All other elements are FALSE.
Present in triplet and compressed column-oriented forms only.j
:"integer"
of length nnzero
(number of non-zero elements). These are the column numbers for
each TRUE element in the matrix. All other elements are FALSE.
Present in triplet and compressed column-oriented forms only.Dim
:"integer"
- the dimensions
of the matrix.signature(from = "dgCMatrix", to = "lgCMatrix")
signature(x = "lgCMatrix")
: returns the transpose
of x