R: Calculates the median for each row (column) in a matrix

colMedians {DelayedMatrixStats}

R Documentation

Calculates the median for each row (column) in a matrix

Description

Calculates the median for each row (column) in a matrix.

Usage

colMedians(x, rows = NULL, cols = NULL, na.rm = FALSE, dim. = dim(x), ...)

rowMedians(x, rows = NULL, cols = NULL, na.rm = FALSE, dim. = dim(x), ...)

## S4 method for signature 'DelayedMatrix'
colMedians(
  x,
  rows = NULL,
  cols = NULL,
  na.rm = FALSE,
  dim. = dim(x),
  force_block_processing = FALSE,
  ...
)

## S4 method for signature 'DelayedMatrix'
rowMedians(
  x,
  rows = NULL,
  cols = NULL,
  na.rm = FALSE,
  dim. = dim(x),
  force_block_processing = FALSE,
  ...
)

Arguments

`x`	A NxK DelayedMatrix.
`rows`	A `vector` indicating subset of rows (and/or columns) to operate over. If `NULL`, no subsetting is done.
`cols`	A `vector` indicating subset of rows (and/or columns) to operate over. If `NULL`, no subsetting is done.
`na.rm`	If `TRUE`, `NA`s are excluded first, otherwise not.
`dim.`	An `integer` `vector` of length two specifying the dimension of `x`, also when not a `matrix`.
`...`	Additional arguments passed to specific methods.
`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.

Details

The implementation of rowMedians() and colMedians() is optimized for both speed and memory. To avoid coercing to doubles (and hence memory allocation), there is a special implementation for integer matrices. That is, if x is an integer matrix, then rowMedians(as.double(x)) (rowMedians(as.double(x))) would require three times the memory of rowMedians(x) (colMedians(x)), but all this is avoided.

Value

Returns a numeric vector of length N (K).

Author(s)

Peter Hickey

Examples

# A DelayedMatrix with a 'Matrix' seed
dm_Matrix <- DelayedArray(Matrix::Matrix(c(rep(1L, 5),
                                           as.integer((0:4) ^ 2),
                                           seq(-5L, -1L, 1L)),
                                         ncol = 3))

colMedians(dm_Matrix)

rowMedians(dm_Matrix)

[Package DelayedMatrixStats version 1.10.1 Index]