PROVESID resolves chemical identifiers and retrieves chemical data, offline first. It keeps local copies of PubChem, EPA CompTox, ChEBI, ChEMBL and ZeroPM, answers from them, and asks the online services only when you let it. It is part of PROVES, a family of packages for prePROcessing and VErification of Substance data.

from provesid import Search

with Search("cas") as s:
    df = s.search(["50-00-0", "64-17-5", "1912-24-9"])
df[["query", "name", "canonical_smiles", "InChIKey", "n_source_support", "confidence"]]

       query          name         canonical_smiles                     InChIKey  n_source_support  confidence
0    50-00-0  formaldehyde                      C=O  WSFSSNUMVMOOMR-UHFFFAOYSA-N                 3      0.9000
1    64-17-5       ethanol                      CCO  LFQSCWFLJHTTHZ-UHFFFAOYSA-N                 4      0.8906
2  1912-24-9      atrazine  CCNc1nc(Cl)nc(NC(C)C)n1  MXWJVTOOROXGIU-UHFFFAOYSA-N                 4      0.9000

Search asks every installed database about each identifier, keeps the structure they agree on, and reports how many sources agreed. The same class takes names, SMILES, InChIs, InChIKeys, DTXSIDs and formulas. No request leaves the machine unless you pass online_fallback=True.

uv pip install provesid                                # from PyPI
uv pip install git+https://github.com/USEtox/PROVESID  # the development version

pip works as well. Python 3.12 or later is required.

The package is small, but the databases are large. None of them ships with the package, and none is downloaded until you ask for it by name:

from provesid import datasets

datasets.status()                                # what is installed, and where
datasets.plan(["pubchem", "comptox", "chebi"])   # what a download would cost
datasets.fetch(["pubchem", "comptox", "chebi"])  # install them
datasets.remove("chembl")                        # reclaim the space

All five are about 21.5 GiB to download and 7.2 GiB to keep. While ChEMBL unpacks, the install needs up to about 38 GiB of free disk space. Downloads resume after an interruption, and each file is checked before it replaces an existing one.

The databases go into one per-user directory shared by every virtual environment on the machine (~/.local/share/provesid on Linux). Set PROVESID_DATA_DIR, or pass data_dir= to any client, to put them elsewhere. Search uses whatever is installed and reports which sources it used in df.attrs["sources_available"].

Each database can also be used directly:

from provesid import PubChemID

with PubChemID(auto_download=False) as db:
    db.cas_to_inchi("50-78-2")
    db.properties(2244, ["MolecularFormula", "InChIKey"], use_online_fallback=False)
    db.descriptors(2244, ["TPSA", "MolLogP"])  # RDKit descriptors, computed locally

from provesid import PubChemAPI, PubChemView, NCIChemicalIdentifierResolver

pc = PubChemAPI()
cid = pc.get_cids_by_name("aspirin")[0]                       # 2244
melting = PubChemView().get_property_table(cid, "Melting Point")
smiles = NCIChemicalIdentifierResolver().resolve("50-00-0", "smiles")  # "C=O"

The online clients share one transport. It paces requests per host, retries what is worth retrying, and stops asking a host that has said to wait. Their answers are cached on disk under ~/.cache/provesid/, or PROVESID_CACHE_DIR.

The CAS Common Chemistry key is stored once and picked up by every later CASCommonChem():

from provesid import set_cas_api_key, CASCommonChem

set_cas_api_key("your-cas-api-key")
CASCommonChem().cas_to_detail("7732-18-5")["name"]  # "Water"

ClassyFireAPI is still in the package, but the ClassyFire service has not classified a new structure since February 2023. For ChEBI chemical classes computed offline, install the chebifier extra; see the Chebifier guide.

The documentation has a quick start, guides and an API reference generated from the docstrings. The tutorials are executed notebooks in examples/:

• Resolving a dataset with Search, the place to start
• PubChem and PubChem View
• ChEMBL
• ChEBI and ChEBI SDF
• ZeroPM
• Chemical Identifier Resolver
• CAS Common Chemistry
• OPSIN

Shorter scripts sit beside them, one folder per feature.

PROVESID learned from these packages and resources:

• PubChemPy (docs)
• CIRpy (docs)
• the IUPAC FAIR Chemistry Cookbook, for tutorials on chemistry web APIs

• UniChem cross-references.
• The ChEBI ontology, read with pronto.
• Structure standardisation with the ChEMBL Structure Pipeline; this may go to IMPROVES instead.

Please open an issue to suggest another source or to report a problem.