Package: sage-numerical-backends-coin
sage-numerical-backends-coin: COIN-OR mixed integer linear programming backend for SageMathCoinBackendhas previously been available as part of theSageMathsource tree,
from which it is built as an "optional extension" when thencbcSage package is installed.However, it is not available in binary distributions such as:the Sage binary distribution (which does not package any optional packages),homebrew (which just uses the Sage binary distribution),Ubuntu (bionic 18.04LTS and several newer versions ship versions of SageMath, with various optional packages including CBC, but not the optional extension module CoinBackend),conda-forge (which ships SageMath and CBC but not the optional extension).FedoraThe present standalone Python packagesage-numerical-backends-coinhas been created from the SageMath sources, version 9.0.beta10.  It can be installed on top of various Sage installations using pip, including all of the above, including older versions of Sage such as 8.1 (as shipped by Ubuntu bionic 18.04LTS).InstallationCBC can either be installed using its Sage package using$ sage -i cbcor any of the methods explained athttps://github.com/coin-or/Cbc.This package finds the CBC installation by means ofpkgconfig.Install this package from PyPI using$ sage -python -m pip install sage-numerical-backends-coinor from GitHub using$ sage -python -m pip install git+https://github.com/mkoeppe/sage-numerical-backends-coin(See.github/workflows/build.ymlfor details about package prerequisites on various systems.)Using this packageTo obtain a solver (backend) instance:sage: from sage_numerical_backends_coin.coin_backend import CoinBackend
sage: CoinBackend()
<sage_numerical_backends_coin.coin_backend.CoinBackend object at 0x7fb72c2c7528>Equivalently:sage: from sage_numerical_backends_coin.coin_backend import CoinBackend
sage: from sage.numerical.backends.generic_backend import get_solver
sage: get_solver(solver=CoinBackend)
<sage_numerical_backends_coin.coin_backend.CoinBackend object at 0x7fe21ffbe2b8>To use this solver (backend) withMixedIntegerLinearProgram:sage: from sage_numerical_backends_coin.coin_backend import CoinBackend
sage: M = MixedIntegerLinearProgram(solver=CoinBackend)
sage: M.get_backend()
<sage_numerical_backends_coin.coin_backend.CoinBackend object at 0x7fb72c2c7868>Setting it as the default backend forMixedIntegerLinearProgram, as of SageMath 9.0.beta10, requires some trickery:sage: import sage_numerical_backends_coin.coin_backend as coin_backend, sage.numerical.backends as backends, sys
sage: sys.modules['sage.numerical.backends.coin_backend'] = backends.coin_backend = coin_backend
sage: default_mip_solver('Coin')To patch this in permanently (at your own risk):$ sage -c 'import os; import sage.numerical.backends as dm; import sage_numerical_backends_coin.coin_backend as sm; s = sm.__file__; f = os.path.basename(s); d = os.path.join(dm.__path__[0], f); (os.path.exists(d) or os.path.lexists(d)) and os.remove(d); os.symlink(s, d);'Or use the scriptpatch_into_sage_module.pyin the source distribution that does the same:$ sage -c 'load("patch_into_sage_module.py")'
Success: Patched in the module as sage.numerical.backends.coin_backendVerify withcheck_get_solver_with_name.pythat the patching script has worked:$ sage -c 'load("check_get_solver_with_name.py")'
Success: get_solver(solver='coin') gives <sage_numerical_backends_coin.coin_backend.CoinBackend object at 0x7f8f20218528>