ompBAM

Workflows

Standard Workflow

library(ompBAM)

# Create a new package template that compiles with ompBAM
pkg_path <- file.path(tempdir(), "MyPkg")
use_ompBAM(pkg_path)

# Retrieve the path to an example BAM file provided by the package
bam_path <- ompBAM::example_BAM("Unsorted")

Input: A destination directory path for the new package.
Output: A fully configured R package directory structure containing C++ templates and configuration files linked to ompBAM.

When to Use

• Developing R packages that require high-performance, multi-threaded processing of BAM files using C++ and OpenMP.
• Writing custom BAM parsing algorithms where you want ompBAM to handle file access, BGZF decompression, and thread management.
• Creating packages that need to run on unsorted and unindexed BAM files (e.g., using pbam_in and pbam1_t APIs).

When NOT to Use

• For standard BAM manipulation or filtering in R without writing C++ code; use Rsamtools or GenomicAlignments instead.
• For querying small genomic regions of sorted and indexed BAM files; use htslib directly as ompBAM is optimized for whole-file sequential reads.

Data Requirements

• Input BAM files (can be unsorted and unindexed).
• A package development environment with Rcpp and a C++ compiler supporting OpenMP (e.g., gcc or clang with OpenMP libraries).

Key Parameters

• path (in use_ompBAM): The directory path where the new package project will be created.
• bam_file: Path to the BAM file to be processed.
• n_threads: Number of threads to use for parallel execution.

Best Practices

• Run devtools::document() on the newly created package to generate the NAMESPACE and export the R wrapper functions.
• Use the #ifdef _OPENMP directive in C++ code to ensure compatibility with systems that do not have OpenMP installed (such as default macOS configurations).
• Call pbam1_t::realize() if you need to store reads in memory across multiple calls of pbam_in::fillReads(), as virtual reads point to temporary buffers.

Common Pitfalls

• macOS Compilation Failure: macOS does not support OpenMP natively. Fix: Install libomp via Homebrew (brew install libomp) and configure compiler flags.
• Memory Corruption with Virtual Reads: Accessing pbam1_t objects after calling fillReads() leads to segmentation faults. Fix: Call realize() on the pbam1_t object to copy the data into persistent memory.
• Requesting Too Many Threads: Requesting more threads than available can degrade performance. Fix: Use a helper function to cap requested threads at omp_get_max_threads().

Alternatives

• Rsamtools: For high-level BAM file manipulation and querying in R.
• GenomicAlignments: For representing and manipulating genomic alignments in R.
• Rcpp: For general C++ integration in R packages without built-in BAM parsing support.

Citations

• Alex C H Wong (2026). ompBAM API Documentation.

References

• Homepage: https://bioconductor.org/packages/ompbam
• Vignette: https://bioconductor.org/packages/release/bioc/vignettes/ompbam/inst/doc/ompBAM-API-Docs.html