OpenBabel (unofficial wheel distribution)

3.1.1.23 verified Mon Apr 27 auth: no python

Unofficial PyPI distribution of OpenBabel (version 3.1.1.23), providing prebuilt wheels for Python ≥3.8. OpenBabel is a chemical toolbox for interconverting chemical file formats, molecular modeling, and cheminformatics. This package is useful when building from source is impractical.

pip install openbabel-wheel

Common errors

error ImportError: No module named openbabel ↓

cause The package is not installed or is installed but named differently.

fix

Run 'pip install openbabel-wheel'. Then use 'import openbabel' (not 'import openbabel-wheel').

error AttributeError: module 'openbabel' has no attribute 'OBMol' ↓

cause You imported the openbabel module but forgot to import its submodule 'openbabel' (the C++ bindings).

fix

Use 'from openbabel import openbabel' then 'openbabel.OBMol()'.

Warnings

gotcha The openbabel package is the top-level library. The familiar 'pybel' module is NOT included in this wheel. You must use openbabel.pybel or direct openbabel API. ↓

fix Use 'from openbabel import pybel' (if pybel is needed) or directly use openbabel.OBMol etc.

deprecated This wheel packages a newer OpenBabel version (3.1.1+) which has breaking changes from the old 'openbabel' package (e.g., removal of certain convenience functions). The official OpenBabel bindings have moved to 'openbabel.openbabel' for the underlying C++ bindings. ↓

fix Check migration guides from OpenBabel 2.x to 3.x. Use 'openbabel.openbabel' for low-level functions.

gotcha On some systems, the wheel may conflict with a system-installed OpenBabel. Ensure no other OpenBabel library is being loaded inadvertently. ↓

fix Run 'import openbabel; print(openbabel.__file__)' to verify which module is loaded.

Imports

openbabel
wrong
```
import openbabel as ob
```
correct
```
import openbabel
```
Common mistake: openbabel is the package name; the module to use is usually its submodules like pybel or openbabel.pybel. But 'import openbabel' works.
OBMol
wrong
```
from openbabel import OBmol
```
correct
```
from openbabel import openbabel
mol = openbabel.OBMol()
```
Case sensitivity: class is OBMol, not OBmol. Also must import openbabel module first.

Quickstart

Basic usage: create an OBMol, read SMILES, print formula.

import openbabel
# Create a molecule
mol = openbabel.OBMol()
# Build from SMILES
conv = openbabel.OBConversion()
conv.SetInAndOutFormats('smi', 'mol')
conv.ReadString(mol, 'CCO')
print('Formula:', mol.GetFormula())