Installation¶

From PyPI¶

pip install molcrafts-molpack

The PyPI package molcrafts-molpack installs a Python module named molpack:

import molpack

Pre-built wheels are published for CPython 3.12 and 3.13 on Linux (manylinux x86-64) and macOS (universal2). Other platforms fall back to the sdist and need a Rust toolchain to build locally.

Frame I/O¶

molcrafts-molpack installs molcrafts-molrs as a dependency. The importable molrs module provides the frame type plus PDB and XYZ readers:

pip install molcrafts-molpack

import molrs
from molpack import InsideBoxRestraint, Molpack, Target

frame = molrs.io.read_pdb("water.pdb")
water = (
    Target(frame, count=100)
    .with_name("water")
    .with_restraint(InsideBoxRestraint([0.0, 0.0, 0.0], [40.0, 40.0, 40.0]))
)
frame = Molpack().with_seed(42).pack([water], max_loops=200)

Target takes a molrs.Frame or molpy.Frame, resolved zero-copy through its FFI capsule.

Building from source¶

Requires a Rust toolchain (1.91+) and maturin:

git clone https://github.com/MolCrafts/molpack
cd molpack/python
pip install maturin
maturin develop --release

This builds against the local molpack Rust crate under ../.

Verification¶

import molrs
from molpack import Target

frame = molrs.Frame.from_dict({
    "blocks": {"atoms": {"x": [0.0], "y": [0.0], "z": [0.0], "element": ["O"]}},
    "meta": {},
})
target = Target(frame, count=1).with_name("mol")
print(target)  # Target(natoms=1, count=1, name=Some("mol"))