colLogSumExps {DelayedMatrixStats} | R Documentation

## Accurately computes the logarithm of the sum of exponentials across rows or columns

### Description

Accurately computes the logarithm of the sum of exponentials across rows or columns.

### Usage

    colLogSumExps(lx, rows = NULL, cols = NULL, na.rm = FALSE,
      dim. = dim(lx), ...)

    rowLogSumExps(lx, rows = NULL, cols = NULL, na.rm = FALSE,
      dim. = dim(lx), ...)

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

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

### Arguments

`lx` | A N \times M 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`, any missing values are ignored, 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 `getOption("DelayedArray.block.size")`) columns (`colFoo()`) or rows (`rowFoo()`) into memory as an ordinary base::array.

### Value

A `numeric` `vector` of length N (K).

### Benchmarking

These methods are implemented in native code and have been optimized for speed and memory.

### See Also

To calculate the same on vectors, `logSumExp`().

### 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))

    colLogSumExps(dm_matrix + 0.1)

    rowLogSumExps(dm_HDF5 + 0.1)

[Package DelayedMatrixStats version 1.0.3 Index]