bio-bam-statistics

bio-bam-statistics is a skill for Claude Code, Codex from PKU-YuanGroup/OpenAI4S. It costs 39 tokens per session (4,412 once invoked), scanned A, a copy of bio-bam-statistics, MIT.

A collection of methods for measuring what is inside an alignment file and how well sequencing reads cover the reference genome. BAM files store compressed read-to-genome alignments.

In plain words
What is it for?
Use it to calculate read counts, mapping rates, chromosome-level statistics, depth profiles, and coverage summaries with samtools or pysam.
Why use it?
Basic counts and coverage checks show whether the data are sufficient and whether alignment problems may affect later analysis.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: positional $N argument.

Good fit Use it to calculate read counts, mapping rates, chromosome-level statistics, depth profiles, and coverage summaries with samtools or pysam.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/pku-yuangroup/openai4s/bio-alignment-files-bam-statistics
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add PKU-YuanGroup/OpenAI4S --skill bio-alignment-files-bam-statistics
Clone the repo
git clone --depth 1 https://github.com/PKU-YuanGroup/OpenAI4S

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for bio-bam-statistics

README.md
[![agentmods](https://agentmods.dev/badge/skills/pku-yuangroup/openai4s/bio-alignment-files-bam-statistics/github.svg)](https://agentmods.dev/skills/pku-yuangroup/openai4s/bio-alignment-files-bam-statistics)
Your own site
<a href="https://agentmods.dev/skills/pku-yuangroup/openai4s/bio-alignment-files-bam-statistics"><img src="https://agentmods.dev/badge/skills/pku-yuangroup/openai4s/bio-alignment-files-bam-statistics/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for bio-bam-statistics

Your own site · 80×15
<a href="https://agentmods.dev/skills/pku-yuangroup/openai4s/bio-alignment-files-bam-statistics"><img src="https://agentmods.dev/badge/skills/pku-yuangroup/openai4s/bio-alignment-files-bam-statistics.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 39 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 4,412 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin 95% copy Near-identical to another mod in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00039 $0.04412
Opus 5 $0.00019 $0.02206
Sonnet 5 $0.00008 $0.00882
Haiku 4.5 $0.00004 $0.00441

Measured 12d ago against content hash 156552233717, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

bio-bam-statistics scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 12d ago.

The scan reads SKILL.md. This mod also ships 1 executable file (scripts/qc_report.py), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

Origin

This is a copy

95% identical to bio-bam-statistics — 12 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

skills/bioskills/bio-alignment-files-bam-statistics/SKILL.md · 434 lines

How it starts

The opening of the file, as written. The whole thing — 434 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Version Compatibility

Reference examples tested with: pysam 0.22+, samtools 1.19+

Before using code patterns, verify installed versions match. If versions differ:

  • Python: pip show <package> then help(module.function) to check signatures
  • CLI: <tool> --version then <tool> --help to confirm flags

If code throws ImportError, AttributeError, or TypeError, introspect the installed package and adapt the example to match the actual API rather than retrying.

BAM Statistics

"Get alignment statistics and coverage from my BAM file" -> Generate read counts, mapping rates, per-chromosome statistics, depth profiles, and coverage summaries.

  • CLI: samtools flagstat, samtools stats, samtools depth, samtools coverage (samtools)
  • Python: pysam.AlignmentFile with pileup() and get_index_statistics() (pysam)

Generate alignment statistics using samtools and pysam.

Quick Summary Commands

Question Best tool Why
Quick read counts by FLAG category samtools flagstat Fast; counts secondary+supp in totals
Per-chromosome counts samtools idxstats Fast (needs index); counts secondary+supp
Insert size, MAPQ, error, GC samtools stats -r ref.fa Comprehensive; feeds MultiQC
Per-position depth (small region) samtools depth or pysam pileup Slow on full genome
Per-position depth (genome-wide) mosdepth 3-10x faster than samtools depth
Per-region coverage (BED) mosdepth --by regions.bed Production default
Coverage histogram / cumulative mosdepth -t 4 --no-per-base Single-pass histogram
Breadth at depth thresholds mosdepth --thresholds 1,10,30,100 Standard exome QC
Targeted enrichment QC picard CollectHsMetrics PCT_OFF_BAIT, FOLD_80_BASE_PENALTY, AT/GC dropout
Cross-sample contamination verifybamid2, somalier FREEMIX < 0.01 expected

What Each Tool Counts (and Doesn't)

Counting category flagstat stats idxstats
Primary alignments in total minus supp raw total sequences mapped column
Secondary secondary line filtered out counted in mapped
Supplementary supplementary line filtered out counted in mapped
Mapping rate denominator total including supp primary only mapped+unmapped

Read the full file on GitHub · 434 lines

Files

What ships with it

2 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 12d ago First seen · 434 lines · 39 tokens per session scan A 156552233717

Subscribe to this mod's changes

bio-bam-statistics is a skill published in the GitHub repository PKU-YuanGroup/OpenAI4S (403 stars, last pushed yesterday), licensed MIT. It adds 39 tokens to every session and 4,412 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. It is 95% identical to bio-bam-statistics, differing in 12 lines, and is treated as a copy.

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