#!/usr/bin/env python
#-*- coding:utf-8 -*-
##
## utils.py
##
"""
Utilities for handling solvers
Contains a static variable `builtin_solvers` that lists
CPMpy solvers (first one is the default solver by default)
=================
List of functions
=================
.. autosummary::
:nosignatures:
param_combinations
"""
import warnings # for deprecation warning
from .gurobi import CPM_gurobi
from .ortools import CPM_ortools
from .minizinc import CPM_minizinc
from .pysat import CPM_pysat
from .z3 import CPM_z3
from .pysdd import CPM_pysdd
from .exact import CPM_exact
[docs]def param_combinations(all_params, remaining_keys=None, cur_params=None):
"""
Recursively yield all combinations of param values
For example usage, see `examples/advanced/hyperparameter_search.py`
- all_params is a dict of {key: list} items, e.g.:
{'val': [1,2], 'opt': [True,False]}
- output is an generator over all {key:value} combinations
of the keys and values. For the example above:
generator([{'val':1,'opt':True},{'val':1,'opt':False},{'val':2,'opt':True},{'val':2,'opt':False}])
"""
if remaining_keys is None or cur_params is None:
# init
remaining_keys = list(all_params.keys())
cur_params = dict()
cur_key = remaining_keys[0]
myresults = [] # (runtime, cur_params)
for cur_value in all_params[cur_key]:
cur_params[cur_key] = cur_value
if len(remaining_keys) == 1:
# terminal, return copy
yield dict(cur_params)
else:
# recursive call
yield from param_combinations(all_params,
remaining_keys=remaining_keys[1:],
cur_params=cur_params)
[docs]class SolverLookup():
[docs] @staticmethod
def base_solvers():
"""
Return ordered list of (name, class) of base CPMpy
solvers
First one is default
"""
return [("ortools", CPM_ortools),
("z3", CPM_z3),
("minizinc", CPM_minizinc),
("gurobi", CPM_gurobi),
("pysat", CPM_pysat),
("pysdd", CPM_pysdd),
("exact", CPM_exact),
]
[docs] @staticmethod
def solvernames():
names = []
for (basename, CPM_slv) in SolverLookup.base_solvers():
if CPM_slv.supported():
names.append(basename)
if hasattr(CPM_slv, "solvernames"):
subnames = CPM_slv.solvernames()
for subn in subnames:
names.append(basename+":"+subn)
return names
[docs] @staticmethod
def get(name=None, model=None):
"""
get a specific solver (by name), with 'model' passed to its constructor
This is the preferred way to initialise a solver from its name
"""
cls = SolverLookup.lookup(name=name)
# check for a 'solver:subsolver' name
subname = None
if name is not None and ':' in name:
_,subname = name.split(':',maxsplit=1)
return cls(model, subsolver=subname)
[docs] @staticmethod
def lookup(name=None):
"""
lookup a solver _class_ by its name
warning: returns a 'class', not an object!
see get() for normal uses
"""
if name is None:
# first solver class
return SolverLookup.base_solvers()[0][1]
# split name if relevant
solvername = name
subname = None
if ':' in solvername:
solvername,_ = solvername.split(':',maxsplit=1)
for (basename, CPM_slv) in SolverLookup.base_solvers():
if basename == solvername:
# found the right solver
return CPM_slv
return None
# using `builtin_solvers` is DEPRECATED, use `SolverLookup` object instead
# Order matters! first is default, then tries second, etc...
builtin_solvers = [CPM_ortools, CPM_gurobi, CPM_minizinc, CPM_pysat, CPM_exact]
[docs]def get_supported_solvers():
"""
Returns a list of solvers supported on this machine.
:return: a list of SolverInterface sub-classes :list[SolverInterface]:
"""
warnings.warn("Deprecated, use Model.solvernames() instead, will be removed in stable version", DeprecationWarning)
return [sv for sv in builtin_solvers if sv.supported()]