SFBM-class: Class SFBM
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SFBM-class

R Documentation

Class SFBM

Description

A reference class for storing and accessing sparse matrix-like data stored in files on disk.

Convert a 'dgCMatrix' or 'dsCMatrix' to an SFBM.

Usage

as_SFBM(spmat, backingfile = tempfile(), compact = FALSE)

Arguments

`spmat`	A 'dgCMatrix' (non-symmetric sparse matrix of type 'double') or 'dsCMatrix' (symmetric sparse matrix of type 'double').
`backingfile`	Path to file where to store data. Extension `.sbk` is automatically added.
`compact`	Whether to use a compact format? Default is `FALSE`. This is useful when non-zero values in columns are contiguous (or almost).

Details

An object of class SFBM has many fields:

⁠$address⁠: address of the external pointer containing the underlying C++ object to be used as a ⁠XPtr<SFBM>⁠ in C++ code
⁠$extptr⁠: (internal) use ⁠$address⁠ instead
⁠$nrow⁠: number of rows
⁠$ncol⁠: number of columns
⁠$nval⁠: number of non-zero values
⁠$p⁠: vector of column positions
⁠$backingfile⁠ or ⁠$sbk⁠: File with extension 'sbk' that stores the data of the SFBM
⁠$rds⁠: 'rds' file (that may not exist) corresponding to the 'sbk' file
⁠$is_saved⁠: whether this object is stored in ⁠$rds⁠?

And some methods:

⁠$save()⁠: Save the SFBM object in ⁠$rds⁠. Returns the SFBM.
⁠$add_columns()⁠: Add new columns from a 'dgCMatrix' or a 'dsCMatrix'.
⁠$dense_acc()⁠: Equivalent to as.matrix(.[ind_row, ind_col]). Use with caution; ind_row and ind_col must be positive indices within range.

Value

The new SFBM.

Examples

spmat2 <- Matrix::Diagonal(4, 0:3)
spmat2[4, 2] <- 5
spmat2[1, 4] <- 6
spmat2[3, 4] <- 7
spmat2

# Stores all (i, x) for x != 0
(X2 <- as_SFBM(spmat2))
matrix(readBin(X2$sbk, what = double(), n = 100), 2)

# Stores only x, but all (even the zero ones) from first to last being not 0
(X3 <- as_SFBM(spmat2, compact = TRUE))
X3$first_i
readBin(X3$sbk, what = double(), n = 100)

bigsparser documentation built on Sept. 11, 2024, 8:29 p.m.