colCollapse,DelayedMatrix-method {DelayedMatrixStats}

R Documentation

Extract one cell from each row (column) of a matrix-like object

Description

Extract one cell from each row (column) of a matrix-like object.

Usage

## S4 method for signature 'DelayedMatrix'
colCollapse(
  x,
  idxs,
  cols = NULL,
  force_block_processing = FALSE,
  ...,
  useNames = NA
)

## S4 method for signature 'DelayedMatrix'
rowCollapse(
  x,
  idxs,
  rows = NULL,
  force_block_processing = FALSE,
  ...,
  useNames = NA
)

Arguments

x	A NxK DelayedMatrix.
idxs	An index vector with the position to extract. It is recycled to match the number of rows (column)
cols	A vector indicating the subset of rows (and/or columns) to operate over. If NULL, no subsetting is done.
force_block_processing	FALSE (the default) means that a seed-aware, optimised method is used (if available). This can be overridden to use the general block-processing strategy by setting this to TRUE (typically not advised). The block-processing strategy loads one or more (depending on \link[DelayedArray]{getAutoBlockSize}()) columns (colFoo()) or rows (rowFoo()) into memory as an ordinary base::array.
...	Additional arguments passed to specific methods.
useNames	If NA, the default behavior of the function about naming support is remained. If FALSE, no naming support is done. Else if TRUE, names attributes of result are set. Only useNames = NA is currently supported, other values are silently ignored.
rows	A vector indicating the subset of rows (and/or columns) to operate over. If NULL, no subsetting is done.

Details

The S4 methods for x of type matrix, array, or numeric call matrixStats::rowCollapse / matrixStats::colCollapse.

Value

Returns a numeric vector of length N (K).

Author(s)

Peter Hickey

See Also

• matrixStats::rowCollapse() and matrixStats::colCollapse() which are used when the input is a matrix or numeric vector.

Examples

# A DelayedMatrix with a 'matrix' seed
dm_matrix <- DelayedArray(matrix(c(rep(1L, 5),
                                   as.integer((0:4) ^ 2),
                                   seq(-5L, -1L, 1L)),
                                 ncol = 3))
# A DelayedMatrix with a 'HDF5ArraySeed' seed
# NOTE: Requires that the HDF5Array package is installed
library(HDF5Array)
dm_HDF5 <- writeHDF5Array(matrix(c(rep(1L, 5),
                                   as.integer((0:4) ^ 2),
                                   seq(-5L, -1L, 1L)),
                                 ncol = 3))

# Extract the 4th row as a vector
# NOTE: An ordinary vector is returned regardless of the backend of
#       the DelayedMatrix object
colCollapse(dm_matrix, 4)
colCollapse(dm_HDF5, 4)

# Extract the 2nd column as a vector
# NOTE: An ordinary vector is returned regardless of the backend of
#       the DelayedMatrix object
rowCollapse(dm_matrix, 2)
rowCollapse(dm_HDF5, 2)

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