spam {spam}

Sparse Matrix Class

Package:

spam

Version:

0.29-3

Description

This group of functions evaluates and coerces changes in class structure.

Usage

spam(x, nrow = 1, ncol = 1, eps = .Spam$eps)

as.spam(x, eps = .Spam$eps)

is.spam(x)

Arguments

x: is a matrix (of either dense or sparse form), a list, vector object or a distance object
nrow: number of rows of matrix
ncol: number of columns of matrix
eps: A tolerance parameter: elements of x such that abs(x) < eps set to zero. Defaults to eps = .Spam$eps

Details

The functions spam and as.spam act like matrix and as.matrix to coerce an object to a sparse matrix object of class spam.

If x is a list, it should contain either two or three elements. In case of the former, the list should contain a n by two matrix of indicies (called ind) and the values. In case of the latter, the list should contain three vectors containing the row, column indices (called i and j) and the values. In both cases partial matching is done. In case there are several triplets with the same i, j, the values are added. eps should be at least as large as .Machine$double.eps.

Values

A valid spam object.
is.spam returns TRUE if x is a spam object.

References

http://en.wikipedia.org/wiki/Sparse_matrix as a start.

Note

The zero matrix has the element zero stored in (1,1).

The functions do not test the presence of NA/NaN/Inf. Virtually all call a Fortran routine with the NAOK=!.Spam$safemode[3] argument, which defaults to FALSE resulting in an error. Hence, the NaN do not always properly propagate through (i.e. spam is not IEEE-754 compliant).

Examples

# old message, do not loop, when you create a large sparse matrix
set.seed(13)
nz <- 128
ln <- nz^2
smat <- spam(0,ln,ln)
is <- sample(ln,nz)
js <- sample(ln,nz)
system.time(for (i in 1:nz) smat[is[i], js[i]] <- i)
system.time(smat[cbind(is,js)] <- 1:nz)
 
getClass("spam")
 
 
 
try(as.spam.numeric(NA))

Author(s)

Reinhard Furrer

Documentation reproduced from package spam, version 0.29-3. License: GPL | file LICENSE