sparseMatrix  R Documentation 
User friendly construction of a compressed, columnoriented, sparse
matrix, inheriting from class
CsparseMatrix
(or
TsparseMatrix
if giveCsparse
is false),
from locations (and values) of its nonzero entries.
This is the recommended user interface rather than direct
new("***Matrix", ....)
calls.
sparseMatrix(i = ep, j = ep, p, x, dims, dimnames, symmetric = FALSE, triangular = FALSE, index1 = TRUE, repr = "C", giveCsparse = (repr == "C"), check = TRUE, use.last.ij = FALSE)
i,j 
integer vectors of the same length specifying the locations
(row and column indices) of the nonzero (or non 
p 
numeric (integer valued) vector of pointers, one for each
column (or row), to the initial (zerobased) index of elements in the
column (or row). Exactly one of 
x 
optional values of the matrix entries. If specified, must be of
the same length as 
dims 
optional, nonnegative, integer, dimensions vector of
length 2. Defaults to 
dimnames 
optional list of 
symmetric 
logical indicating if the resulting matrix should be symmetric. In that case, only the lower or upper triangle needs to be specified via (i/j/p). 
triangular 
logical indicating if the resulting matrix should be triangular. In that case, the lower or upper triangle needs to be specified via (i/j/p). 
index1 
logical scalar. If 
repr 

giveCsparse 
(deprecated, replaced with 
check 
logical indicating if a validity check is performed; do
not set to 
use.last.ij 
logical indicating if in the case of repeated,
i.e., duplicated pairs (i_k, j_k) only the last one should be
used. The default, 
Exactly one of the arguments i
, j
and p
must be
missing.
In typical usage, p
is missing, i
and j
are
vectors of positive integers and x
is a numeric vector. These
three vectors, which must have the same length, form the triplet
representation of the sparse matrix.
If i
or j
is missing then p
must be a
nondecreasing integer vector whose first element is zero. It
provides the compressed, or “pointer” representation of the row
or column indices, whichever is missing. The expanded form of p
,
rep(seq_along(dp),dp)
where dp < diff(p)
, is used as
the (1based) row or column indices.
You cannot set both singular
and triangular
to true;
rather use Diagonal()
(or its alternatives, see there).
The values of i
, j
, p
and index1
are used
to create 1based index vectors i
and j
from which a
TsparseMatrix
is constructed, with numerical
values given by x
, if nonmissing. Note that in that case,
when some pairs (i_k,j_k) are repeated (aka
“duplicated”), the corresponding x_k are added, in
consistency with the definition of the
"TsparseMatrix"
class, unless use.last.ij
is set to true.
By default, when repr = "C"
, the CsparseMatrix
derived from this triplet form is returned, where repr = "R"
now
allows to directly get an RsparseMatrix
and
repr = "T"
leaves the result as TsparseMatrix
.
The reason for returning a CsparseMatrix
object
instead of the triplet format by default is that the compressed column
form is easier to work with when performing matrix operations. In
particular, if there are no zeros in x
then a
CsparseMatrix
is a unique representation of the
sparse matrix.
A sparse matrix, by default (from repr = "C"
) in compressed,
columnoriented form, as an R object inheriting from both
CsparseMatrix
and generalMatrix
.
You do need to use index1 = FALSE
(or add + 1
to i
and j
) if you want use the 0based i
(and
j
) slots from existing sparse matrices.
Matrix(*, sparse=TRUE)
for the constructor of
such matrices from a dense matrix. That is easier in small
sample, but much less efficient (or impossible) for large matrices,
where something like sparseMatrix()
is needed.
Further bdiag
and Diagonal
for (block)diagonal and
bandSparse
for banded sparse matrix constructors.
Random sparse matrices via rsparsematrix()
.
The standard R xtabs(*, sparse=TRUE)
, for sparse tables
and sparse.model.matrix()
for building sparse model
matrices.
Consider CsparseMatrix
and similar class
definition help files.
## simple example i < c(1,3:8); j < c(2,9,6:10); x < 7 * (1:7) (A < sparseMatrix(i, j, x = x)) ## 8 x 10 "dgCMatrix" summary(A) str(A) # note that *internally* 0based row indices are used (sA < sparseMatrix(i, j, x = x, symmetric = TRUE)) ## 10 x 10 "dsCMatrix" (tA < sparseMatrix(i, j, x = x, triangular= TRUE)) ## 10 x 10 "dtCMatrix" stopifnot( all(sA == tA + t(tA)) , identical(sA, as(tA + t(tA), "symmetricMatrix"))) ## dims can be larger than the maximum row or column indices (AA < sparseMatrix(c(1,3:8), c(2,9,6:10), x = 7 * (1:7), dims = c(10,20))) summary(AA) ## i, j and x can be in an arbitrary order, as long as they are consistent set.seed(1); (perm < sample(1:7)) (A1 < sparseMatrix(i[perm], j[perm], x = x[perm])) stopifnot(identical(A, A1)) ## The slots are 0index based, so try( sparseMatrix(i=A@i, p=A@p, x= seq_along(A@x)) ) ## fails and you should say so: 1indexing is FALSE: sparseMatrix(i=A@i, p=A@p, x= seq_along(A@x), index1 = FALSE) ## the (i,j) pairs can be repeated, in which case the x's are summed (args < data.frame(i = c(i, 1), j = c(j, 2), x = c(x, 2))) (Aa < do.call(sparseMatrix, args)) ## explicitly ask for elimination of such duplicates, so ## that the last one is used: (A. < do.call(sparseMatrix, c(args, list(use.last.ij = TRUE)))) stopifnot(Aa[1,2] == 9, # 2+7 == 9 A.[1,2] == 2) # 2 was *after* 7 ## for a pattern matrix, of course there is no "summing": (nA < do.call(sparseMatrix, args[c("i","j")])) dn < list(LETTERS[1:3], letters[1:5]) ## pointer vectors can be used, and the (i,x) slots are sorted if necessary: m < sparseMatrix(i = c(3,1, 3:2, 2:1), p= c(0:2, 4,4,6), x = 1:6, dimnames = dn) m str(m) stopifnot(identical(dimnames(m), dn)) sparseMatrix(x = 2.72, i=1:3, j=2:4) # recycling x sparseMatrix(x = TRUE, i=1:3, j=2:4) # recycling x, > "lgCMatrix" ## no 'x' > patter*n* matrix: (n < sparseMatrix(i=1:6, j=rev(2:7)))# > ngCMatrix ## an empty sparse matrix: (e < sparseMatrix(dims = c(4,6), i={}, j={})) ## a symmetric one: (sy < sparseMatrix(i= c(2,4,3:5), j= c(4,7:5,5), x = 1:5, dims = c(7,7), symmetric=TRUE)) stopifnot(isSymmetric(sy), identical(sy, ## switch i <> j {and transpose } t( sparseMatrix(j= c(2,4,3:5), i= c(4,7:5,5), x = 1:5, dims = c(7,7), symmetric=TRUE)))) ## rsparsematrix() calls sparseMatrix() : M1 < rsparsematrix(1000, 20, nnz = 200) summary(M1) ## pointers example in converting from other sparse matrix representations. if(require(SparseM) && packageVersion("SparseM") >= 0.87 && nzchar(dfil < system.file("extdata", "rua_32_ax.rua", package = "SparseM"))) { X < model.matrix(read.matrix.hb(dfil)) XX < sparseMatrix(j = X@ja, p = X@ia  1L, x = X@ra, dims = X@dimension) validObject(XX) ## Alternatively, and even more user friendly : X. < as(X, "Matrix") # or also X2 < as(X, "sparseMatrix") stopifnot(identical(XX, X.), identical(X., X2)) }
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