delarr_mmap: Create a delayed matrix from a memory-mapped file

In delarr: Lazy Delayed Arrays with Fused Execution

Create a delayed matrix from a memory-mapped file

Description

Uses the mmap package to lazily read slices from a binary file on demand. The file must contain raw numeric data in column-major order (R's default).

Usage

delarr_mmap(path, nrow, ncol, mode = NULL)

Arguments

path	Path to the binary file containing matrix data.
nrow	Number of rows in the matrix.
ncol	Number of columns in the matrix.
mode	mmap mode object specifying data type. Default is double().

Value

A delarr that streams data from the memory-mapped file.

Note

This backend supports 2D matrices only. For N-d arrays, use delarr_hdf5() or wrap an in-memory array with delarr().

Examples

if (requireNamespace("mmap", quietly = TRUE)) {
  # Create a binary file with matrix data
  mat <- matrix(1:20, nrow = 4, ncol = 5)
  tf <- tempfile()
  writeBin(as.double(mat), tf)

  # Load as delayed array
  darr <- delarr_mmap(tf, nrow = 4, ncol = 5)
  darr

  # Apply operations and collect
  result <- darr |> d_map(~ .x * 2) |> collect()
  result

  # Clean up
  unlink(tf)
}

delarr documentation built on July 1, 2026, 1:06 a.m.