pysam

Overview

Use pysam for low-level, streaming access to HTSlib-supported genomic formats:

• AlignmentFile and AlignedSegment for SAM/BAM/CRAM
• VariantFile, VariantHeader, and VariantRecord for VCF/BCF
• FastaFile for indexed FASTA and FastxFile for sequential FASTA/FASTQ
• TabixFile for BGZF-compressed, tabix-indexed BED/GFF/GTF/custom tables
• pysam.samtools and pysam.bcftools for wrapped command dispatchers

Current upstream baseline: pysam 0.24.0 (27 April 2026), wrapping HTSlib/samtools/bcftools 1.23.1. Read references/sources.md before updating version-specific guidance.

Installation

Use the pinned release for reproducible work:

uv pip install "pysam==0.24.0"

Confirm the runtime:

import pysam

print(pysam.__version__)           # 0.24.0
print(pysam.__samtools_version__)  # 1.23.1

Prebuilt wheels are available for supported macOS and Linux platforms. A source build needs a C compiler and HTSlib build dependencies; read the official installation guide linked from references/sources.md.

First Decide

Before writing code:

1. Identify the real format, compression, sort order, and available index.
2. De…