Source code for qiskit_optimization.applications.graph_optimization_application

# This code is part of a Qiskit project.
#
# (C) Copyright IBM 2018, 2025.
#
# This code is licensed under the Apache License, Version 2.0. You may
# obtain a copy of this license in the LICENSE.txt file in the root directory
# of this source tree or at http://www.apache.org/licenses/LICENSE-2.0.
#
# Any modifications or derivative works of this code must retain this
# copyright notice, and modified files need to carry a notice indicating
# that they have been altered from the originals.

"""An abstract class for graph optimization application classes."""
from __future__ import annotations

from abc import abstractmethod

import networkx as nx
import numpy as np

import qiskit_optimization.optionals as _optionals

from ..algorithms import OptimizationResult
from .optimization_application import OptimizationApplication




class GraphOptimizationApplication(OptimizationApplication):
    """
    An abstract class for graph optimization applications.
    """

    def __init__(self, graph: nx.Graph | np.ndarray | list) -> None:
        """
        Args:
            graph: A graph representing a problem. It can be specified directly as a
                `NetworkX <https://networkx.org/>`_ graph,
                or as an array or list format suitable to build out a NetworkX graph.
        """
        # The view of the graph is stored which means the graph can not be changed.
        self._graph = nx.Graph(graph).copy(as_view=True)



    @_optionals.HAS_MATPLOTLIB.require_in_call
    def draw(
        self,
        result: OptimizationResult | np.ndarray | None = None,
        pos: dict[int, np.ndarray] | None = None,
    ) -> None:
        """Draw a graph with the result. When the result is None, draw an original graph without
        colors.

        Args:
            result: The calculated result for the problem
            pos: The positions of nodes
        """
        if result is None:
            nx.draw(self._graph, pos=pos, with_labels=True)
        else:
            self._draw_result(result, pos)


    @abstractmethod
    def _draw_result(
        self,
        result: OptimizationResult | np.ndarray,
        pos: dict[int, np.ndarray] | None = None,
    ) -> None:
        """Draw the result with colors

        Args:
            result : The calculated result for the problem
            pos: The positions of nodes
        """
        pass

    @property
    def graph(self) -> nx.Graph:
        """Getter of the graph

        Returns:
            A graph for a problem
        """
        return self._graph