5bf70b691f
* CMake has not been updated yet * bazel was compiling at least last week bazel: disable math opt facility_location.py missing some dependencies...
288 lines
10 KiB
Python
288 lines
10 KiB
Python
# Copyright 2010-2025 Google LLC
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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"""Data structures for linear and quadratic constraints.
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In contrast to BoundedLinearExpression and related structures, there is no
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offset inside the inequality.
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This is not part of the MathOpt public API, do not depend on it externally.
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"""
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import dataclasses
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import math
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from typing import Mapping, Optional, Union
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from ortools.math_opt.python import bounded_expressions
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from ortools.math_opt.python import variables
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_BoundedLinearExpressions = (
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variables.LowerBoundedLinearExpression,
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variables.UpperBoundedLinearExpression,
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variables.BoundedLinearExpression,
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)
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_BoundedQuadraticExpressions = (
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variables.LowerBoundedLinearExpression,
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variables.UpperBoundedLinearExpression,
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variables.BoundedLinearExpression,
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variables.LowerBoundedQuadraticExpression,
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variables.UpperBoundedQuadraticExpression,
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variables.BoundedQuadraticExpression,
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)
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_BoundedExpressions = (
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bounded_expressions.LowerBoundedExpression,
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bounded_expressions.UpperBoundedExpression,
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bounded_expressions.BoundedExpression,
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)
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def _bool_error() -> TypeError:
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return TypeError(
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"Unsupported type for bounded_expr argument:"
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" bool. This error can occur when trying to add != constraints "
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"(which are not supported) or inequalities/equalities with constant "
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"left-hand-side and right-hand-side (which are redundant or make a "
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"model infeasible)."
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)
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@dataclasses.dataclass
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class NormalizedLinearInequality:
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"""Represents an inequality lb <= expr <= ub where expr's offset is zero."""
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lb: float
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ub: float
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coefficients: Mapping[variables.Variable, float]
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def __init__(
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self,
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*,
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lb: Optional[float],
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ub: Optional[float],
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expr: Optional[variables.LinearTypes],
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) -> None:
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"""Raises a ValueError if expr's offset is infinite."""
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lb = -math.inf if lb is None else lb
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ub = math.inf if ub is None else ub
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expr = 0.0 if expr is None else expr
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if not isinstance(expr, (int, float, variables.LinearBase)):
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raise TypeError(
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f"Unsupported type for expr argument: {type(expr).__name__!r}."
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)
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flat_expr = variables.as_flat_linear_expression(expr)
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if math.isinf(flat_expr.offset):
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raise ValueError(
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"Trying to create a linear constraint whose expression has an"
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" infinite offset."
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)
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self.lb = lb - flat_expr.offset
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self.ub = ub - flat_expr.offset
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self.coefficients = flat_expr.terms
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def _normalize_bounded_linear_expression(
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bounded_expr: variables.BoundedLinearTypes,
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) -> NormalizedLinearInequality:
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"""Converts a bounded linear expression into a NormalizedLinearInequality."""
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if isinstance(bounded_expr, variables.VarEqVar):
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return NormalizedLinearInequality(
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lb=0.0,
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ub=0.0,
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expr=bounded_expr.first_variable - bounded_expr.second_variable,
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)
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elif isinstance(bounded_expr, _BoundedExpressions):
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if isinstance(bounded_expr.expression, (int, float, variables.LinearBase)):
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return NormalizedLinearInequality(
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lb=bounded_expr.lower_bound,
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ub=bounded_expr.upper_bound,
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expr=bounded_expr.expression,
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)
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else:
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raise TypeError(
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"Bad type of expression in bounded_expr:"
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f" {type(bounded_expr.expression).__name__!r}."
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)
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else:
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raise TypeError(f"bounded_expr has bad type: {type(bounded_expr).__name__!r}.")
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# TODO(b/227214976): Update the note below and link to pytype bug number.
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# Note: bounded_expr's type includes bool only as a workaround to a pytype
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# issue. Passing a bool for bounded_expr will raise an error in runtime.
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def as_normalized_linear_inequality(
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bounded_expr: Optional[Union[bool, variables.BoundedLinearTypes]] = None,
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*,
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lb: Optional[float] = None,
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ub: Optional[float] = None,
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expr: Optional[variables.LinearTypes] = None,
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) -> NormalizedLinearInequality:
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"""Builds a NormalizedLinearInequality.
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If bounded_expr is not None, then all other arguments must be None.
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If expr has a nonzero offset, it will be subtracted from both lb and ub.
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When bounded_expr is unset and a named argument is unset, we use the defaults:
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* lb: -math.inf
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* ub: math.inf
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* expr: 0
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Args:
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bounded_expr: a linear inequality describing the constraint.
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lb: The lower bound when bounded_expr is None.
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ub: The upper bound if bounded_expr is None.
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expr: The expression when bounded_expr is None.
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Returns:
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A NormalizedLinearInequality representing the linear constraint.
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"""
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if isinstance(bounded_expr, bool):
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raise _bool_error()
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if bounded_expr is not None:
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if lb is not None:
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raise AssertionError(
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"lb cannot be specified when bounded_expr is not None."
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)
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if ub is not None:
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raise AssertionError(
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"ub cannot be specified when bounded_expr is not None."
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)
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if expr is not None:
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raise AssertionError(
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"expr cannot be specified when bounded_expr is not None"
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)
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return _normalize_bounded_linear_expression(bounded_expr)
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# Note: NormalizedLinearInequality() will runtime check the type of expr.
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return NormalizedLinearInequality(lb=lb, ub=ub, expr=expr)
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@dataclasses.dataclass
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class NormalizedQuadraticInequality:
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"""Represents an inequality lb <= expr <= ub where expr's offset is zero."""
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lb: float
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ub: float
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linear_coefficients: Mapping[variables.Variable, float]
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quadratic_coefficients: Mapping[variables.QuadraticTermKey, float]
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def __init__(
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self,
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*,
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lb: Optional[float] = None,
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ub: Optional[float] = None,
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expr: Optional[variables.QuadraticTypes] = None,
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) -> None:
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"""Raises a ValueError if expr's offset is infinite."""
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lb = -math.inf if lb is None else lb
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ub = math.inf if ub is None else ub
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expr = 0.0 if expr is None else expr
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if not isinstance(
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expr, (int, float, variables.LinearBase, variables.QuadraticBase)
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):
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raise TypeError(
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f"Unsupported type for expr argument: {type(expr).__name__!r}."
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)
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flat_expr = variables.as_flat_quadratic_expression(expr)
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if math.isinf(flat_expr.offset):
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raise ValueError(
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"Trying to create a quadratic constraint whose expression has an"
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" infinite offset."
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)
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self.lb = lb - flat_expr.offset
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self.ub = ub - flat_expr.offset
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self.linear_coefficients = flat_expr.linear_terms
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self.quadratic_coefficients = flat_expr.quadratic_terms
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def _normalize_bounded_quadratic_expression(
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bounded_expr: Union[variables.BoundedQuadraticTypes, variables.BoundedLinearTypes],
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) -> NormalizedQuadraticInequality:
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"""Converts a bounded quadratic expression into a NormalizedQuadraticInequality."""
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if isinstance(bounded_expr, variables.VarEqVar):
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return NormalizedQuadraticInequality(
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lb=0.0,
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ub=0.0,
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expr=bounded_expr.first_variable - bounded_expr.second_variable,
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)
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elif isinstance(bounded_expr, _BoundedExpressions):
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if isinstance(
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bounded_expr.expression,
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(int, float, variables.LinearBase, variables.QuadraticBase),
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):
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return NormalizedQuadraticInequality(
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lb=bounded_expr.lower_bound,
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ub=bounded_expr.upper_bound,
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expr=bounded_expr.expression,
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)
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else:
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raise TypeError(
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"bounded_expr.expression has bad type:"
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f" {type(bounded_expr.expression).__name__!r}."
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)
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else:
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raise TypeError(f"bounded_expr has bad type: {type(bounded_expr).__name__!r}.")
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# TODO(b/227214976): Update the note below and link to pytype bug number.
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# Note: bounded_expr's type includes bool only as a workaround to a pytype
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# issue. Passing a bool for bounded_expr will raise an error in runtime.
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def as_normalized_quadratic_inequality(
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bounded_expr: Optional[
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Union[bool, variables.BoundedLinearTypes, variables.BoundedQuadraticTypes]
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] = None,
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*,
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lb: Optional[float] = None,
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ub: Optional[float] = None,
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expr: Optional[variables.QuadraticTypes] = None,
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) -> NormalizedQuadraticInequality:
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"""Builds a NormalizedLinearInequality.
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If bounded_expr is not None, then all other arguments must be None.
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If expr has a nonzero offset, it will be subtracted from both lb and ub.
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When bounded_expr is unset and a named argument is unset, we use the defaults:
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* lb: -math.inf
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* ub: math.inf
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* expr: 0
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Args:
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bounded_expr: a quadratic inequality describing the constraint.
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lb: The lower bound when bounded_expr is None.
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ub: The upper bound if bounded_expr is None.
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expr: The expression when bounded_expr is None.
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Returns:
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A NormalizedLinearInequality representing the linear constraint.
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"""
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if isinstance(bounded_expr, bool):
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raise _bool_error()
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if bounded_expr is not None:
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if lb is not None:
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raise AssertionError(
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"lb cannot be specified when bounded_expr is not None."
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)
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if ub is not None:
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raise AssertionError(
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"ub cannot be specified when bounded_expr is not None."
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)
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if expr is not None:
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raise AssertionError(
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"expr cannot be specified when bounded_expr is not None"
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)
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return _normalize_bounded_quadratic_expression(bounded_expr)
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return NormalizedQuadraticInequality(lb=lb, ub=ub, expr=expr)
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