DelayedMatrix-utils {DelayedArray} | R Documentation

## Common operations on DelayedMatrix objects

### Description

Common operations on DelayedMatrix objects.

### Details

In addition to the operations supported on DelayedArray objects, DelayedMatrix objects support the following operations:

Delayed operations:

- `t`

Block-processed operations:

- `rowsum` and `colsum`

- matrix multiplication (%*%) of an ordinary matrix by a DelayedMatrix object

- matrix row/col summarization (see `?`DelayedMatrix-stats``)

### See Also

- `rowsum` in the base package for computing column sums across rows of an ordinary matrix for each level of a grouping variable.

- DelayedArray-utils for common operations on DelayedArray objects.

- DelayedArray-stats for statistical functions on DelayedArray objects.

- DelayedMatrix-stats for DelayedMatrix row/col summarization.

- `setRealizationBackend` for how to set a realization backend.

- `writeHDF5Array` in the HDF5Array package for writing an array-like object to an HDF5 file and other low-level utilities to control the location of automatically created HDF5 datasets.

- DelayedArray objects.

- HDF5Array objects in the HDF5Array package.

- array objects in base R.

### Examples

    ## ---------------------------------------------------------------------
    ## rowsum() / colsum()
    ## ---------------------------------------------------------------------
    library(HDF5Array)
    set.seed(123)
    m0 <- matrix(runif(14400000), ncol=2250,
                 dimnames=list(NULL, sprintf("C%04d", 1:2250)))
    M0 <- writeHDF5Array(m0, chunkdim=c(200, 250))
    dimnames(M0) <- dimnames(m0)

    ## --- rowsum() ---

    group <- sample(90, nrow(M0), replace=TRUE)  # define groups of rows
    rs <- rowsum(M0, group)
    rs[1:5, 1:8]
    rs2 <- rowsum(M0, group, reorder=FALSE)
    rs2[1:5, 1:8]

    ## Let's see block processing in action:
    DelayedArray:::set_verbose_block_processing(TRUE)
    setAutoBlockSize(2e6)
    rs3 <- rowsum(M0, group)
    setAutoBlockSize()
    DelayedArray:::set_verbose_block_processing(FALSE)

    ## Sanity checks:
    stopifnot(all.equal(rowsum(m0, group), rs))
    stopifnot(all.equal(rowsum(m0, group, reorder=FALSE), rs2))
    stopifnot(all.equal(rs, rs3))

    ## --- colsum() ---

    group <- sample(30, ncol(M0), replace=TRUE)  # define groups of cols
    cs <- colsum(M0, group)
    cs[1:5, 1:7]
    cs2 <- colsum(M0, group, reorder=FALSE)
    cs2[1:5, 1:7]

    ## Sanity checks:
    stopifnot(all.equal(colsum(m0, group), cs))
    stopifnot(all.equal(cs, t(rowsum(t(m0), group))))
    stopifnot(all.equal(cs, t(rowsum(t(M0), group))))
    stopifnot(all.equal(colsum(m0, group, reorder=FALSE), cs2))
    stopifnot(all.equal(cs2, t(rowsum(t(m0), group, reorder=FALSE))))
    stopifnot(all.equal(cs2, t(rowsum(t(M0), group, reorder=FALSE))))

    ## ---------------------------------------------------------------------
    ## MATRIX MULTIPLICATION
    ## ---------------------------------------------------------------------
    library(HDF5Array)
    toy_h5 <- system.file("extdata", "toy.h5", package="HDF5Array")
    h5ls(toy_h5)
    M1 <- HDF5Array(toy_h5, "M1")

    ## Matrix multiplication is not delayed: the output matrix is realized
    ## block by block. The current "realization backend" controls where
    ## realization happens e.g. in memory if set to NULL or in an HDF5 file
    ## if set to "HDF5Array". See '?realize' for more information about
    ## "realization backends".
    ## The output matrix is returned as a DelayedMatrix object with no delayed
    ## operations on it. The exact class of the object depends on the backend
    ## e.g. it will be HDF5Matrix with "HDF5Array" backend.

    m <- matrix(runif(50000), ncol=nrow(M1))

    ## Set backend to NULL for in-memory realization:
    setRealizationBackend()
    P1 <- m %*% M1
    P1

    ## Set backend to HDF5Array for realization in HDF5 file:
    setRealizationBackend("HDF5Array")

    ## With the HDF5Array backend, the output matrix will be written to an
    ## automatic location on disk:
    getHDF5DumpFile()  # HDF5 file where the output matrix will be written
    lsHDF5DumpFile()

    P2 <- m %*% M1
    P2

    lsHDF5DumpFile()

    ## Use setHDF5DumpFile() and setHDF5DumpName() from the HDF5Array package
    ## to control the location of automatically created HDF5 datasets.

    stopifnot(identical(dim(P1), dim(P2)),
              all.equal(as.array(P1), as.array(P2)))

[Package DelayedArray version 0.10.0 Index]