pybnb
=====
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A parallel branch-and-bound engine for Python. (https://pybnb.readthedocs.io)
This software is copyright (c) by Gabriel A. Hackebeil (gabe.hackebeil@gmail.com).
This software is released under the MIT software license.
This license, including disclaimer, is available in the 'LICENSE' file.
Quick Start
-----------
**Define a problem:**
.. code:: python
# simple.py
import pybnb
class Simple(pybnb.Problem):
def __init__(self):
self.bounds = [0.0,1.0]
def sense(self):
return pybnb.minimize
def objective(self):
return round(self.bounds[1] - self.bounds[0], 3)
def bound(self):
return -(self.bounds[1] - self.bounds[0])**2
def save_state(self, node):
node.state = self.bounds
def load_state(self, node):
self.bounds = node.state
def branch(self):
L, U = self.bounds
mid = 0.5 * (L + U)
for l,u in [(L,mid), (mid,U)]:
child = pybnb.Node()
child.state = (l,u)
yield child
**Write a solve script:**
.. code:: python
# solve_simple.py
import simple
problem = simple.Simple()
results = pybnb.solve(problem,
absolute_gap=1e-9)
**Run the script:**
.. code:: bash
$ mpirun -np 4 python solve_simple.py
Using non-default solver options:
- absolute_gap: 1e-09 (default: 0)
Starting branch & bound solve:
- dispatcher pid: 34902 (Ozymandias.local)
- worker processes: 3
---------------------------------------------------------------------------------------------------------------------------
Nodes | Objective Bounds | Work
Expl Unexpl | Incumbent Bound Rel. Gap Abs. Gap | Time (s) Nodes/Sec Imbalance Idle
0 1 | inf -inf inf% inf | 0.0 0.00 0.00% 0
* 1 2 | 1 -1 200.0000000% 2 | 0.0 1226.99 300.00% 1
* 2 3 | 0.5 -1 150.0000000% 1.5 | 0.0 2966.04 150.00% 0
* 4 5 | 0.25 -0.25 50.0000000% 0.5 | 0.0 8081.95 75.00% 0
* 8 9 | 0.125 -0.0625 18.7500000% 0.1875 | 0.0 12566.90 37.50% 0
Expl Unexpl | Incumbent Bound Rel. Gap Abs. Gap | Time (s) Nodes/Sec Imbalance Idle
* 16 17 | 0.062 -0.015625 7.7625000% 0.077625 | 0.0 15352.74 18.75% 0
* 32 33 | 0.031 -0.00390625 3.4906250% 0.03490625 | 0.0 15981.49 18.75% 0
* 64 65 | 0.016 -0.0009765625 1.6976563% 0.0169765625 | 0.0 18740.68 18.75% 0
* 128 129 | 0.008 -0.0002441406 0.8244141% 0.008244140625 | 0.0 21573.51 11.72% 0
* 256 257 | 0.004 -6.103516e-05 0.4061035% 0.004061035156 | 0.0 22166.96 8.20% 0
Expl Unexpl | Incumbent Bound Rel. Gap Abs. Gap | Time (s) Nodes/Sec Imbalance Idle
* 512 513 | 0.002 -1.525879e-05 0.2015259% 0.002015258789 | 0.0 21177.00 5.86% 0
* 1024 1025 | 0.001 -3.814697e-06 0.1003815% 0.001003814697 | 0.1 19978.42 9.38% 0
* 2048 2049 | 0 -9.536743e-07 0.0000954% 9.536743164e-07 | 0.1 21606.45 5.42% 0
24029 24030 | 0 -1.490116e-08 0.0000015% 1.490116119e-08 | 1.1 21961.03 5.98% 0
46159 46160 | 0 -3.72529e-09 0.0000004% 3.725290298e-09 | 2.1 22120.75 5.73% 0
Expl Unexpl | Incumbent Bound Rel. Gap Abs. Gap | Time (s) Nodes/Sec Imbalance Idle
65537 65538 | 0 -9.313226e-10 0.0000001% 9.313225746e-10 | 3.0 22459.50 6.20% 0
---------------------------------------------------------------------------------------------------------------------------
Absolute optimality tolerance met
Optimal solution found!
solver results:
- solution_status: optimal
- termination_condition: optimality
- objective: 0
- bound: -9.313226e-10
- absolute_gap: 9.313226e-10
- relative_gap: 9.313226e-10
- nodes: 65537
- wall_time: 2.96 s
- best_node: Node(objective=0)
Number of Workers: 3
Load Imbalance: 6.20%
- min: 21355 (proc rank=3)
- max: 22710 (proc rank=1)
Average Worker Timing:
- queue: 80.78% [avg time: 109.6 us, count: 65537]
- load_state: 0.44% [avg time: 596.1 ns, count: 65537]
- bound: 0.59% [avg time: 796.1 ns, count: 65537]
- objective: 3.52% [avg time: 4.7 us, count: 65537]
- branch: 3.36% [avg time: 4.6 us, count: 65537]
- other: 11.31% [avg time: 15.3 us, count: 65537]
.. |Travis-Status| image:: https://travis-ci.org/ghackebeil/pybnb.svg?branch=master
:target: https://travis-ci.org/ghackebeil/pybnb
.. |Appveyor-Status| image:: https://ci.appveyor.com/api/projects/status/gfbrxja9v08rm7a2?svg=true
:target: https://ci.appveyor.com/project/ghackebeil/pybnb
.. |Coverage-Status| image:: https://codecov.io/gh/ghackebeil/pybnb/branch/master/graph/badge.svg
:target: https://codecov.io/gh/ghackebeil/pybnb
.. |Documentation-Status| image:: https://readthedocs.org/projects/pybnb/badge/?version=latest
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.. |PyPI-Versions| image:: https://img.shields.io/pypi/pyversions/pybnb.svg
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.. |PyPI-Downloads| image:: https://img.shields.io/pypi/dm/pybnb.svg
:target: https://pypistats.org/packages/pybnb
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"description": "pybnb\n=====\n\n|PyPI-Status| |PyPI-Versions| |Codacy-Grade|\n\n|Travis-Status| |Appveyor-Status| |Coverage-Status| |Documentation-Status|\n\n|PyPI-Downloads|\n\nA parallel branch-and-bound engine for Python. (https://pybnb.readthedocs.io)\n\nThis software is copyright (c) by Gabriel A. Hackebeil (gabe.hackebeil@gmail.com).\n\nThis software is released under the MIT software license.\nThis license, including disclaimer, is available in the 'LICENSE' file.\n\nQuick Start\n-----------\n\n**Define a problem:**\n\n.. code:: python\n\n # simple.py\n\n import pybnb\n class Simple(pybnb.Problem):\n def __init__(self):\n self.bounds = [0.0,1.0]\n def sense(self):\n return pybnb.minimize\n def objective(self):\n return round(self.bounds[1] - self.bounds[0], 3)\n def bound(self):\n return -(self.bounds[1] - self.bounds[0])**2\n def save_state(self, node):\n node.state = self.bounds\n def load_state(self, node):\n self.bounds = node.state\n def branch(self):\n L, U = self.bounds\n mid = 0.5 * (L + U)\n for l,u in [(L,mid), (mid,U)]:\n child = pybnb.Node()\n child.state = (l,u)\n yield child\n\n**Write a solve script:**\n\n.. code:: python\n\n # solve_simple.py\n\n import simple\n problem = simple.Simple()\n results = pybnb.solve(problem,\n absolute_gap=1e-9)\n\n**Run the script:**\n\n.. code:: bash\n\n $ mpirun -np 4 python solve_simple.py\n\n Using non-default solver options:\n - absolute_gap: 1e-09 (default: 0)\n\n Starting branch & bound solve:\n - dispatcher pid: 34902 (Ozymandias.local)\n - worker processes: 3\n ---------------------------------------------------------------------------------------------------------------------------\n Nodes | Objective Bounds | Work \n Expl Unexpl | Incumbent Bound Rel. Gap Abs. Gap | Time (s) Nodes/Sec Imbalance Idle\n 0 1 | inf -inf inf% inf | 0.0 0.00 0.00% 0\n * 1 2 | 1 -1 200.0000000% 2 | 0.0 1226.99 300.00% 1\n * 2 3 | 0.5 -1 150.0000000% 1.5 | 0.0 2966.04 150.00% 0\n * 4 5 | 0.25 -0.25 50.0000000% 0.5 | 0.0 8081.95 75.00% 0\n * 8 9 | 0.125 -0.0625 18.7500000% 0.1875 | 0.0 12566.90 37.50% 0\n Expl Unexpl | Incumbent Bound Rel. Gap Abs. Gap | Time (s) Nodes/Sec Imbalance Idle\n * 16 17 | 0.062 -0.015625 7.7625000% 0.077625 | 0.0 15352.74 18.75% 0\n * 32 33 | 0.031 -0.00390625 3.4906250% 0.03490625 | 0.0 15981.49 18.75% 0\n * 64 65 | 0.016 -0.0009765625 1.6976563% 0.0169765625 | 0.0 18740.68 18.75% 0\n * 128 129 | 0.008 -0.0002441406 0.8244141% 0.008244140625 | 0.0 21573.51 11.72% 0\n * 256 257 | 0.004 -6.103516e-05 0.4061035% 0.004061035156 | 0.0 22166.96 8.20% 0\n Expl Unexpl | Incumbent Bound Rel. Gap Abs. Gap | Time (s) Nodes/Sec Imbalance Idle\n * 512 513 | 0.002 -1.525879e-05 0.2015259% 0.002015258789 | 0.0 21177.00 5.86% 0\n * 1024 1025 | 0.001 -3.814697e-06 0.1003815% 0.001003814697 | 0.1 19978.42 9.38% 0\n * 2048 2049 | 0 -9.536743e-07 0.0000954% 9.536743164e-07 | 0.1 21606.45 5.42% 0\n 24029 24030 | 0 -1.490116e-08 0.0000015% 1.490116119e-08 | 1.1 21961.03 5.98% 0\n 46159 46160 | 0 -3.72529e-09 0.0000004% 3.725290298e-09 | 2.1 22120.75 5.73% 0\n Expl Unexpl | Incumbent Bound Rel. Gap Abs. Gap | Time (s) Nodes/Sec Imbalance Idle\n 65537 65538 | 0 -9.313226e-10 0.0000001% 9.313225746e-10 | 3.0 22459.50 6.20% 0\n ---------------------------------------------------------------------------------------------------------------------------\n \n Absolute optimality tolerance met\n Optimal solution found!\n \n solver results:\n - solution_status: optimal\n - termination_condition: optimality\n - objective: 0\n - bound: -9.313226e-10\n - absolute_gap: 9.313226e-10\n - relative_gap: 9.313226e-10\n - nodes: 65537\n - wall_time: 2.96 s\n - best_node: Node(objective=0)\n \n Number of Workers: 3\n Load Imbalance: 6.20%\n - min: 21355 (proc rank=3)\n - max: 22710 (proc rank=1)\n Average Worker Timing:\n - queue: 80.78% [avg time: 109.6 us, count: 65537]\n - load_state: 0.44% [avg time: 596.1 ns, count: 65537]\n - bound: 0.59% [avg time: 796.1 ns, count: 65537]\n - objective: 3.52% [avg time: 4.7 us, count: 65537]\n - branch: 3.36% [avg time: 4.6 us, count: 65537]\n - other: 11.31% [avg time: 15.3 us, count: 65537]\n\n\n.. |Travis-Status| image:: https://travis-ci.org/ghackebeil/pybnb.svg?branch=master\n :target: https://travis-ci.org/ghackebeil/pybnb\n.. |Appveyor-Status| image:: https://ci.appveyor.com/api/projects/status/gfbrxja9v08rm7a2?svg=true\n :target: https://ci.appveyor.com/project/ghackebeil/pybnb\n.. |Coverage-Status| image:: https://codecov.io/gh/ghackebeil/pybnb/branch/master/graph/badge.svg\n :target: https://codecov.io/gh/ghackebeil/pybnb\n.. |Documentation-Status| image:: https://readthedocs.org/projects/pybnb/badge/?version=latest\n :target: http://pybnb.readthedocs.io/en/latest/?badge=latest\n.. |PyPI-Status| image:: https://img.shields.io/pypi/v/pybnb.svg\n :target: https://pypi.python.org/pypi/pybnb\n.. |PyPI-Versions| image:: https://img.shields.io/pypi/pyversions/pybnb.svg\n :target: https://pypi.org/project/pybnb\n.. |Codacy-Grade| image:: https://img.shields.io/lgtm/grade/python/g/ghackebeil/pybnb.svg?logo=lgtm&logoWidth=18\n :target: https://lgtm.com/projects/g/ghackebeil/pybnb/context:python\n.. |PyPI-Downloads| image:: https://img.shields.io/pypi/dm/pybnb.svg\n :target: https://pypistats.org/packages/pybnb",
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