Framework for the Ising model and QUBO.
OpenJij : Framework for the Ising model and QUBO.

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  • python >= 3.8
  • (optional) gcc >= 7.0.0
  • (optional) cmake >= 3.22
  • (optional) Ninja

OpenJij Website

Change <strong>IMPORT</strong>

  • OpenJij >= v0.5.0
import openjij.cxxjij
  • OpenJij <= v0.4.9
import cxxjij


install via pip

Note: (2023/08/09) GPGPU algorithms will no longer be supported.

# Binary
$ pip install openjij
# From Source
$ pip install --no-binary=openjij openjij

install via pip from source codes

To install OpenJij from source codes, please install CMake first then install OpenJij.

cmake setup

If you want to use instead of PIP, You will need to install CMake>=3.22.\ We are Highly recommended install CMake via PYPI.

$ pip install -U cmake

Make sure the enviroment path for CMake is set correctly.

install OpenJij

$ pip install --no-binary=openjij openjij

install from github repository

$ git clone
$ cd openjij
$ python -m pip install -vvv .

For Contributor

Use pre-commit for auto chech before git commit. .pre-commit-config.yaml

# pipx install pre-commit
# or
# pip install pre-commit
pre-commit install



$ python -m venv .venv
$ . .venv/bin/activate
$ pip install pip-tools
$ pip-compile setup.cfg
$ pip-compile
$ pip-sync requirements.txt dev-requirements.txt
$ source .venv/bin/activate
$ export CMAKE_BUILD_TYPE=Debug
$ python --force-cmake install --build-type Debug -G Ninja
$ python --build-type Debug test
$ python -m coverage html


$ mkdir build
$ cmake -DCMAKE_BUILD_TYPE=Debug -S . -B build
$ cmake --build build --parallel
$ cd build
$ ./tests/cxxjij_test
# Alternatively Use CTest
$ ctest --extra-verbose --parallel --schedule-random

Needs: CMake > 3.22, C++17

  • Format
$ pip-compile
$ pip-sync format-requirements.txt
$ python -m isort
$ python -m black
  • Aggressive Format
$ python -m isort --force-single-line-imports --verbose ./openjij
$ python -m autoflake --in-place --recursive --remove-all-unused-imports --ignore-init-module-imports --remove-unused-variables ./openjij
$ python -m autopep8 --in-place --aggressive --aggressive --recursive ./openjij
$ python -m isort ./openjij
$ python -m black ./openjij
  • Lint
$ pip-compile setup.cfg
$ pip-compile
$ pip-compile
$ pip-sync requirements.txt dev-requirements.txt lint-requirements.txt
$ python -m flake8
$ python -m mypy
$ python -m pyright

Python Documentation

Use Juyter Book for build documentation.
With KaTeX
Need: Graphviz

$ pip-compile setup.cfg
$ pip-compile
$ pip-compile
$ pip-sync requirements.txt build-requirements.txt doc-requirements.txt

Please place your document to docs/tutorialeither markdown or jupyter notebook style.

$ pip install -vvv .
$ jupyter-book build docs --all

How to use

Python example

import openjij as oj
sampler = oj.SASampler()
response = sampler.sample_ising(h={0: -1}, J={(0,1): -1})
# [[1,1]]
# with indices
response = sampler.sample_ising(h={'a': -1}, J={('a','b'): 1})
[{index: s for index, s in zip(response.indices, state)} for state in response.states]
# [{'b': -1, 'a': 1}]


About us

This product is maintained by Jij Inc.

Please visit our website for more information!


Copyright 2023 Jij Inc.

Licensed under the Apache License, Version 2.0 (the "License");\ you may not use this file except in compliance with the License.\ You may obtain a copy of the License at

Unless required by applicable law or agreed to in writing, software\ distributed under the License is distributed on an "AS IS" BASIS,\ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.\ See the License for the specific language governing permissions and\ limitations under the License.