Spectral File Format Conversion

spectral-file-format-conversion

Summary

Extract and standardize spectral data from GNPS molecular networking job archives into NPLinker-compatible file formats (spectra.mgf, molecular_families.tsv, annotations.tsv, file_mappings.tsv/csv). This skill bridges heterogeneous GNPS workflow outputs (GNPS1 vs. GNPS2, METABOLOMICS-SNETS vs. FEATURE-BASED-MOLECULAR-NETWORKING) into a unified input schema for downstream metabolomics data integration.

When to use

When you have a GNPS molecular networking job archive (downloaded as a .zip or compressed archive) and need to prepare metabolomics spectra and molecular family data for NPLinker integration. Specifically: you have a GNPS task ID, access to the GNPS download URL, and you need to decompose the archive into the four standard NPLinker files (spectra.mgf, molecular_families.tsv, annotations.tsv, file_mappings.tsv or file_mappings.csv) to feed into npl.load_data().

When NOT to use

• Input is not from GNPS (e.g., spectra already in a non-GNPS format or from a different molecular networking platform).
• The four required output files already exist in the correct NPLinker format and naming scheme in the target directory.
• The GNPS job failed or the archive is corrupted and does not contain valid spectra.mgf or molecular_families data.

Inputs

• GNPS task ID (string identifier for a GNPS molecular networking job)
• GNPS job archive (compressed .zip or .tar.gz file downloaded from GNPS)

Outputs

• spectra.mgf (MS/MS spectral data in MGF format)
• molecular_families.tsv (molecular networking clusters/groups)
• annotations.tsv (metabolite annotations and spectral assignments)
• file_mappings.tsv or file_mappings.csv (link between spectra and samples)

How to apply

First, initialize a GNPSDownloader with the GNPS task ID and a local downloads directory path, then call its download() method to fetch the job archive and retrieve its file path. Second, initialize a GNPSExtractor with the downloaded archive path and a target gnps directory path; the extractor identifies the GNPS workflow type (METABOLOMICS-SNETS, METABOLOMICS-SNETS-V2, FEATURE-BASED-MOLECULAR-NETWORKING for GNPS1, or classical_networking_workflow, feature_based_molecular_networking_workflow for GNPS2) and extracts the relevant data files. Third, rename and move the extracted files to the standard NPLinker names (spectra.mgf, molecular_families.tsv, annotations.tsv, file_mappings.tsv or file_mappings.csv). Finally, verify that all four required files are present, accessible, and correctly named in the gnps directory; this ensures downstream data loading will succeed.

Related tools

• GNPSDownloader (Fetches GNPS molecular networking job archive from GNPS server and returns local file path) — https://github.com/NPLinker/nplinker
• GNPSExtractor (Decompresses archive and identifies GNPS workflow type to extract constituent spectra and molecular family files) — https://github.com/NPLinker/nplinker
• nplinker (Python framework integrating the download, extraction, and standardization workflow for GNPS data into metabolomics-genomics data mining) — https://github.com/NPLinker/nplinker

Examples

from nplinker.gnps import GNPSDownloader, GNPSExtractor; downloader = GNPSDownloader(task_id='task_001', downloads_dir='./downloads'); archive_path = downloader.download(); extractor = GNPSExtractor(archive_path, gnps_dir='./gnps'); extractor.extract()

Evaluation signals

• All four required files (spectra.mgf, molecular_families.tsv, annotations.tsv, file_mappings.tsv or file_mappings.csv) are present and readable in the gnps directory.
• spectra.mgf contains valid MS/MS spectrum records with precursor m/z and fragment ion data in MGF format.
• molecular_families.tsv contains cluster IDs and spectra membership, with structure consistent with GNPS output.
• file_mappings.tsv or file_mappings.csv correctly links spectrum identifiers to sample/file names.
• npl.load_data() successfully ingests the four files without schema or format errors.

Limitations

• The skill requires network connectivity to download from GNPS servers (GNPS1 at https://gnps.ucsd.edu or GNPS2 at https://gnps2.org); offline or restricted access will fail.
• Workflow type detection relies on identifying expected file structures within the archive; non-standard or malformed archives may not decompose correctly.
• The skill assumes the GNPS job completed successfully; incomplete or failed GNPS runs will produce incomplete or missing output files.
• File naming and directory structure are rigid; deviations from the four standard file names will cause downstream npl.load_data() to fail.

Evidence

• [other] GNPSDownloader fetches a GNPS molecular networking job archive and returns its file path: "Initialize a GNPSDownloader with the GNPS task ID and a downloads directory path, then call the download() method to fetch the job archive and retrieve its local file path."
• [other] GNPSExtractor decomposes archive based on workflow type: "Initialize a GNPSExtractor with the downloaded archive path and the target gnps directory path, then call the extraction method to decompress the archive and identify the relevant data files based on"
• [other] Files must be renamed to standard NPLinker names: "Rename and move the extracted files to the standard NPLinker names (spectra.mgf, molecular_families.tsv, annotations.tsv, file_mappings.tsv or file_mappings.csv) in the gnps directory."
• [other] Verification step ensures all files present: "Verify that all four required files are present and accessible in the gnps directory with correct naming and format."
• [readme] NPLinker integrates genomics and metabolomics data: "NPLinker is a python framework for data mining microbial natural products by integrating genomics and metabolomics data."