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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 3.12–3.13 on Linux (x86_64, aarch64), macOS (x86_64, arm64), and Windows (x86_64).

molpack accepts molrs.Frame objects directly — the recommended way to load PDB and XYZ files:

pip install molcrafts-molpack molcrafts-molrs

import molrs
from molpack import InsideBoxRestraint, Molpack, Target

frame = molrs.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 a molpy.Frame), resolved zero-copy through its FFI capsule, so one of molcrafts-molrs / molcrafts-molpy is required to build targets from a structure.

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"]}}
})
target = Target(frame, count=1).with_name("mol")
print(target)  # Target(natoms=1, count=1, name=Some("mol"))