Matrix (version 1.0-4)

externalFormats: Read and write external matrix formats

Description

Read matrices stored in the Harwell-Boeing or MatrixMarket formats or write sparseMatrix objects to one of these formats.

Usage

readHB(file)
readMM(file)
writeMM(obj, file, ...)

Arguments

obj

a real sparse matrix

file

for writeMM - the name of the file to be written. For readHB and readMM the name of the file to read, as a character scalar. The names of files storing matrices in the Harwell-Boeing format usually end in <

...

optional additional arguments. Currently none are used in any methods.

Value

• The readHB and readMM functions return an object that inherits from the "Matrix" class. Methods for the writeMM generic functions usually return NULL and, as a side effect, the matrix obj is written to file in the MatrixMarket format (writeMM).

References

http://math.nist.gov/MatrixMarket

http://www.cise.ufl.edu/research/sparse/matrices

Examples

str(pores <- readMM(system.file("external/pores_1.mtx",
                                package = "Matrix")))
str(utm <- readHB(system.file("external/utm300.rua",
                               package = "Matrix")))
str(lundA <- readMM(system.file("external/lund_a.mtx",
                                package = "Matrix")))
str(lundA <- readHB(system.file("external/lund_a.rsa",
                                package = "Matrix")))
## NOTE: The following examples take quite some time
## ----  even on a fast internet connection:
if(FALSE) # the URL has been corrected, but we need an un-tar step!
str(sm <-
 readHB(gzcon(url("http://www.cise.ufl.edu/research/sparse/RB/Boeing/msc00726.tar.gz"))))

str(jgl009 <-
 readMM(gzcon(url("ftp://math.nist.gov/pub/MatrixMarket2/Harwell-Boeing/counterx/jgl009.mtx.gz"))))
data(KNex)
writeMM(KNex$mm, "mmMM.mtx")

## very simple export - in triplet format - to text file:
data(CAex)
s.CA <- summary(CAex)
message("writing to ", outf <- tempfile())
write.table(s.CA, file = outf, row.names=FALSE)
## and read it back -- showing off  sparseMatrix():
dd <- read.table(outf, header=TRUE)
mm <- do.call(sparseMatrix, dd)
stopifnot(all.equal(mm, CAex, tol=1e-15))