Snakemake Dag Generation And Execution

snakemake-dag-generation-and-execution

Summary

Construct and execute a Snakemake directed acyclic graph (DAG) to orchestrate DEIMoS multi-dimensional mass spectrometry workflows, automating mzML ingestion, peak detection, feature alignment, and CCS calibration across local or cluster compute environments. This skill ensures reproducible, scalable processing of high-dimensional LC-IMS-MS/MS data with explicit rule dependencies and configurable execution modes.

When to use

Use this skill when you have multiple mzML or mzML.gz files from LC-IMS-MS/MS instruments and need to apply DEIMoS feature detection, alignment, and calibration operations in a reproducible, traceable manner. Applies when you want to parallelize processing across multiple input files (via --count and --start filtering), enforce rule ordering (mzML → MS1 peakpicking → MS2 extraction → feature alignment → CCS calibration → isotope detection), and manage compute resources (local cores or cluster job scheduling).

When NOT to use

• Input data are already in feature table format (aligned .h5 or .csv); use this skill only on raw mzML files that require instrument-agnostic, N-dimensional processing.
• Single mzML file with no need for cross-sample alignment or batch processing; simpler DEIMoS Python API invocations suffice.
• When deterministic rule ordering is not required or workflow dependencies are already resolved; use Snakemake DAG generation only if you need explicit, traceable rule lineage.

Inputs

• mzML or mzML.gz files (input/ directory)
• YAML configuration file (config.yaml or --config PATH) with algorithm parameters and rule settings
• Optional tuning or reference data files (e.g., example_tune_pos.h5 for CCS calibration)
• DEIMoS CLI arguments (--count, --start, --cores, --cluster, --jobs, --dryrun, --unlock, --touch)

Outputs

• Snakemake directed acyclic graph (DAG) defining rule dependencies and per-file workflow
• HDF5 (.h5) feature tables (aligned features, MS1/MS2 peaks, isotope signatures)
• Calibration artifacts (CCS calibration parameters, retention time/drift time models)
• Execution logs and status reports (per-rule, per-file)
• Populated output/ directory with all processed and aligned results

How to apply

First, parse DEIMoS CLI arguments (--config, --count, --start, --cores, --cluster, --jobs) to configure Snakemake execution mode (local or cluster) and set file limits. Auto-detect .mzML and .mzML.gz input files in the input/ directory; apply file-count filtering (--count N, starting at --start IDX) to subset the DAG size if needed. Load a YAML configuration file (default: config.yaml or --config PATH) to parameterize Snakemake rules and DEIMoS algorithm settings (e.g., threshold=500 for peakpicking). Generate the DAG defining the per-run workflow with explicit rule dependencies: mzML → MS1 peakpicking → MS2 extraction/deconvolution → feature alignment → CCS calibration → isotope detection. Execute the DAG via Snakemake with the specified executor (local with --cores N, or cluster with --cluster PATH and --jobs N); optionally perform dry-run (--dryrun), unlock (--unlock), or touch (--touch) operations. Verify all expected output files are produced in the output/ directory (aligned features, MS1/MS2 results, calibration artifacts).

Related tools

• Snakemake (Workflow orchestration engine; defines, schedules, and executes per-file DAGs with rule dependencies, parallelization, and cluster integration)
• DEIMoS (Python API and CLI target for Snakemake rules; performs mzML parsing, feature detection, alignment, CCS calibration, isotope detection, and MS/MS deconvolution) — https://github.com/pnnl/deimos
• conda (Virtual environment management; ensures reproducible, isolated DEIMoS and Snakemake dependency resolution)
• Python (Primary implementation language for DEIMoS API and Snakemake rule logic; enables data I/O, configuration parsing, and post-processing)
• ProteoWizard msconvert (Optional pre-processing tool; converts vendor instrument formats to mzML input for Snakemake workflow)

Examples

snakemake --config config.yaml --count 5 --start 0 --cores 4 --dryrun

Evaluation signals

• DAG visualization (snakemake --dag output) shows all expected rules with correct dependencies: mzML → MS1 → MS2 → alignment → CCS → isotope.
• All input files matching --count and --start filtering are processed (verify input file count matches DAG node count).
• Output directory contains expected .h5 files (aligned features, MS1/MS2 peaks, isotope signatures) with non-zero record counts.
• Snakemake execution log reports 0 failed rules and matches expected runtime parallelization (--cores or --jobs utilization).
• Dry-run (--dryrun) output lists all planned rule invocations without errors; actual execution (re-run without --dryrun) completes with matching file manifest.

Limitations

• DEIMoS is largely agnostic to acquisition instrumentation, but mzML files must contain valid accession fields (e.g., MS:1000016 for retention_time, MS:1002476 for drift_time); missing accessions cause parsing failures.
• Snakemake DAG generation requires valid YAML configuration; malformed config files or missing algorithm parameters will fail rule instantiation.
• Cluster execution requires a valid --cluster submission template (e.g., SLURM) and network connectivity; local mode is more robust but limited to single-machine parallelization.
• Feature alignment and CCS calibration performance depend on sample representativeness and data quality; poor signal-to-noise or sparse features may produce low-confidence alignments.
• No changelog or versioning guarantees are documented; reproducibility across DEIMoS versions may require explicit dependency pinning in conda environment files.

Evidence

• [other] mzML → MS1 peakpicking → MS2 extraction/deconvolution → feature alignment → CCS calibration → isotope detection: "per-run workflow: mzML → MS1 peakpicking → MS2 extraction/deconvolution → feature alignment → CCS calibration → isotope detection"
• [other] Parse DEIMoS CLI arguments (--config, --count, --start, --cores, --cluster, --jobs): "Parse the DEIMoS CLI arguments (--config, --count, --start, --cores, --cluster, --jobs) to configure the Snakemake workflow execution mode"
• [other] Auto-detect .mzML and .mzML.gz input files in the input/ directory; apply file-count filtering: "Auto-detect .mzML and .mzML.gz input files in the input/ directory; apply file-count filtering (--count N, starting at --start IDX) to limit the DAG size"
• [other] Load the YAML configuration file (default: config.yaml, or --config PATH) to parameterize Snakemake rules: "Load the YAML configuration file (default: config.yaml, or --config PATH) to parameterize Snakemake rules and algorithm settings"
• [other] Execute the DAG via Snakemake with the specified executor (local with --cores N, or cluster with --cluster PATH and --jobs N): "Execute the DAG via Snakemake with the specified executor (local with --cores N, or cluster with --cluster PATH and --jobs N); optionally perform dry-run (--dryrun), unlock (--unlock), or touch"
• [methods] A Snakemake configuration file in YAML format is required.: "A Snakemake configuration file in YAML format is required."
• [other] DEIMoS loads mzML.gz files by parsing accession fields (e.g., 'MS:1000016' for retention_time, 'MS:1002476' for drift_time): "DEIMoS loads mzML.gz files by parsing accession fields (e.g., 'MS:1000016' for retention_time, 'MS:1002476' for drift_time), then applies threshold filtering (threshold=500)"
• [readme] Functionality includes feature detection, feature alignment, collision cross section (CCS) calibration, isotope detection, and MS/MS spectral deconvolution: "Functionality includes feature detection, feature alignment, collision cross section (CCS) calibration, isotope detection, and MS/MS spectral deconvolution"