Constraints

This module implements a declarative langauge of constraints on sequence values. The language consists of:

Examples in this file will reference the following SCHEMA:

SCHEMA = OrderedDict()
SCHEMA["aa1"] = ["P", "L", None]
SCHEMA["aa2"] = ["N", "Y",  "T", None]
SCHEMA["aa3"] = ["R", "S"]
class pyroed.constraints.Constraint[source]

Bases: abc.ABC

Abstract base class for constraints.

Derived classes must implement the __call__() method.

class pyroed.constraints.Function(fn: Callable[[torch.Tensor], torch.Tensor])[source]

Bases: pyroed.constraints.Constraint

Constrains the choices by a black box user-provided function.

Example:

def constraint(choices: torch.Tensor):
    # Put an upper bound on the sequences.
    return choices.float().sum(-1) < 8

CONSTRAINTS.append(Function(constraint))
Parameters

fn (callable) – A function inputting a batch of encoded sequences and returning a batched feasability tensor.

class pyroed.constraints.TakesValue(name: str, value: Optional[str])[source]

Bases: pyroed.constraints.Constraint

Constrains a site to take a fixed value.

Example:

CONSTRAINTS.append(TakesValue("aa1", "P"))
Parameters

  • name (str) – Name of a sequence variable in the schema.

  • value – The value that the variable can take.

class pyroed.constraints.TakesValues(name: str, *values: Optional[str])[source]

Bases: pyroed.constraints.Constraint

Constrains a site to take one of a set of values.

Example:

CONSTRAINTS.append(TakesValue("aa1", "P", "L"))
Parameters

  • name (str) – Name of a sequence variable in the schema.

  • *values – Values that the variable can take.

class pyroed.constraints.AllDifferent(*names: str)[source]

Bases: pyroed.constraints.Constraint

Constrains a set of sites to all have distinct values.

Example:

CONSTRAINTS.append(AllDifferent("aa1", "aa2", "aa3"))
Parameters

*names (str) – Names of sequence variables that should be distinct.

class pyroed.constraints.Not(arg: pyroed.constraints.Constraint)[source]

Bases: pyroed.constraints.Constraint

Negates a constraints.

Example:

CONSTRAINTS.append(Not(TakesValue("aa1", "P")))
Parameters

arg (Constraint) – A constraint.

class pyroed.constraints.And(lhs: pyroed.constraints.Constraint, rhs: pyroed.constraints.Constraint)[source]

Bases: pyroed.constraints.Constraint

Conjoins two constraints.

Example:

CONSTRAINTS.append(And(TakesValue("aa1", None), TakesValue("aa2", None)))
Parameters
class pyroed.constraints.Or(lhs: pyroed.constraints.Constraint, rhs: pyroed.constraints.Constraint)[source]

Bases: pyroed.constraints.Constraint

Disjoins two constraints.

Example:

CONSTRAINTS.append(Or(TakesValue("aa1", None), TakesValue("aa2", None)))
Parameters
class pyroed.constraints.Xor(lhs: pyroed.constraints.Constraint, rhs: pyroed.constraints.Constraint)[source]

Bases: pyroed.constraints.Constraint

Exclusive or among constraints. Equivalent to Not(Iff(lhs, rhs)).

Example:

CONSTRAINTS.append(Xor(TakesValue("aa1", None), TakesValue("aa2", None)))
Parameters
class pyroed.constraints.IfThen(lhs: pyroed.constraints.Constraint, rhs: pyroed.constraints.Constraint)[source]

Bases: pyroed.constraints.Constraint

Conditional between constraints.

Example:

CONSTRAINTS.append(IfThen(TakesValue("aa1", None), TakesValue("aa2", None)))
Parameters
class pyroed.constraints.Iff(lhs: pyroed.constraints.Constraint, rhs: pyroed.constraints.Constraint)[source]

Bases: pyroed.constraints.Constraint

Equality among constraints.

Exmaple:

CONSTRAINTS.append(Iff(TakesValue("aa1", None), TakesValue("aa2", None)))
Parameters