position_engine

PositionEngine

PositionEngine(balance_engine: BalanceEngine)

Bases: Observer, Notifier

PositionEngine computes point positions, distances, and coordinates.

Observes a BalanceEngine and updates its internal geometry state whenever the balance engine notifies observers. It is also a Notifier itself, so downstream observers (e.g. a PlotEngine) are automatically notified after every update.

Users can work with a PositionEngine directly — without any Plotly dependency — to obtain span points, support positions, obstacle coordinates, and point-to-cable distances.

Parameters:

Name	Type	Description	Default
balance_engine	BalanceEngine	BalanceEngine to observe.	required

Examples:

>>> from mechaphlowers.core.geometry.position_engine import PositionEngine
>>> pos_engine = PositionEngine(balance_engine)
>>> pos_engine.get_supports_points()
array(...)
>>> pos_engine.get_spans_points(frame="section")
array(...)

Source code in src/mechaphlowers/core/geometry/position_engine.py

def __init__(self, balance_engine: BalanceEngine) -> None:
    Notifier.__init__(self)
    balance_engine.bind_to(self)

    self.distance_engine = DistanceEngine()
    self.initialize_engine(balance_engine)
    self.reset(balance_engine=balance_engine)

beta property

beta: ndarray

Load angle (\(\beta\)) for each span, in radians.

add_obstacle

add_obstacle(
    name: str,
    span_index: int,
    coords: ndarray,
    object_type: str = 'ground',
    support_reference: Literal['left', 'right'] = 'left',
    span_length: ndarray | None = None,
)

Delegate to ObstacleArray.add_obstacle.

Source code in src/mechaphlowers/core/geometry/position_engine.py

def add_obstacle(
    self,
    name: str,
    span_index: int,
    coords: np.ndarray,
    object_type: str = "ground",
    support_reference: Literal['left', 'right'] = 'left',
    span_length: np.ndarray | None = None,
):
    """Delegate to [`ObstacleArray.add_obstacle`][mechaphlowers.entities.arrays.ObstacleArray.add_obstacle]."""
    self.obstacle_array.add_obstacle(
        name,
        span_index,
        coords,
        object_type,
        support_reference,
        span_length,
    )
    # Replace by a Notifier/Observer pattern?
    self.coords_calculator.refresh_obstacles()

add_obstacle_array

add_obstacle_array(obstacle_array: ObstacleArray) -> None

Attach an ObstacleArray for coordinate computation.

Source code in src/mechaphlowers/core/geometry/position_engine.py

def add_obstacle_array(self, obstacle_array: ObstacleArray) -> None:
    """Attach an `ObstacleArray` for coordinate computation."""
    self.obstacle_array = obstacle_array
    self.coords_calculator.obstacle_array = self.obstacle_array
    self.coords_calculator.refresh_obstacles()

delete_obstacle

delete_obstacle(
    obs_names_to_delete: str | list[str],
) -> None

Delegate to ObstacleArray.delete_obstacle.

Source code in src/mechaphlowers/core/geometry/position_engine.py

def delete_obstacle(self, obs_names_to_delete: str | list[str]) -> None:
    """Delegate to [`ObstacleArray.delete_obstacle`][mechaphlowers.entities.arrays.ObstacleArray.delete_obstacle]."""
    self.obstacle_array.delete_obstacle(obs_names_to_delete)
    self.coords_calculator.refresh_obstacles()

delete_point

delete_point(obs_name: str, point_index: int) -> None

Delegate to ObstacleArray.delete_point.

Source code in src/mechaphlowers/core/geometry/position_engine.py

def delete_point(self, obs_name: str, point_index: int) -> None:
    """Delegate to [`ObstacleArray.delete_point`][mechaphlowers.entities.arrays.ObstacleArray.delete_point]."""
    self.obstacle_array.delete_point(obs_name, point_index)
    self.coords_calculator.refresh_obstacles()

get_distances_from_obstacles

get_distances_from_obstacles() -> (
    dict[str, dict[int, DistanceResult]]
)

Compute distances for all obstacles to their respective spans.

Only in absolute coordiantes.

{ 'obs_0': {0: DistanceResult, 1: DistanceResult}, 'obs_1': {0: DistanceResult} }

Returns:

Name	Type	Description
dict	dict[str, dict[int, DistanceResult]]	dictionary of DistanceResult, sorted by obstacles

Source code in src/mechaphlowers/core/geometry/position_engine.py

def get_distances_from_obstacles(
    self,
) -> dict[str, dict[int, DistanceResult]]:
    """Compute distances for all obstacles to their respective spans.

    Only in absolute coordiantes.

    {
        'obs_0': {0: DistanceResult, 1: DistanceResult},
        'obs_1': {0: DistanceResult}
    }

    Returns:
        dict: dictionary of DistanceResult, sorted by obstacles
    """

    distance_dict_result = {}
    # self.coord_calculator.compute_obstacle_coords()?
    obstacle_sparse_points = self.coords_calculator.obstacles_points
    # index of obstacle point among total points
    loop_index = 0
    for (
        obstacle_name,
        obstacle_coords_array,
    ) in obstacle_sparse_points.dict_coords().items():
        current_distance_result = {}
        # create dict {0: DistanceResult, 1:: DistanceResult, ...} per obstacle
        for obstacle_coords in obstacle_coords_array:
            span_index = obstacle_sparse_points.span_index[loop_index]
            point_index = obstacle_sparse_points.point_index[loop_index]
            distance_result = self.point_distance(
                span_index, obstacle_coords
            )
            current_distance_result[point_index] = distance_result
            loop_index += 1
        distance_dict_result[obstacle_name] = current_distance_result

    return distance_dict_result

get_insulators_points

get_insulators_points() -> ndarray

Return insulator attachment points (absolute section frame).

Source code in src/mechaphlowers/core/geometry/position_engine.py

def get_insulators_points(self) -> np.ndarray:
    """Return insulator attachment points (absolute section frame)."""
    return self.coords_calculator.get_insulators().points(True)

get_loads_coords

get_loads_coords(
    project: bool = False, frame_index: int = 0
) -> dict

Return a dictionary of load coordinates indexed by span.

If loads exist on spans 0 and 2, the result looks like: {0: [x0, y0, z0], 2: [x2, y2, z2]}.

Parameters:

Name	Type	Description	Default
project	bool	True to project all objects into a support frame (for 2-D graphs). Defaults to False.	False
frame_index	int	Index of the support frame used for projection. Must be in [0, nb_supports - 1]. Unused when project is False. Defaults to 0.	0

Returns:

Type	Description
dict	Dict mapping span index (int) to coordinate array of shape
dict	(3,).

Source code in src/mechaphlowers/core/geometry/position_engine.py

def get_loads_coords(
    self, project: bool = False, frame_index: int = 0
) -> dict:
    """Return a dictionary of load coordinates indexed by span.

    If loads exist on spans 0 and 2, the result looks like:
    ``{0: [x0, y0, z0], 2: [x2, y2, z2]}``.

    Args:
        project: ``True`` to project all objects into a support frame
            (for 2-D graphs). Defaults to ``False``.
        frame_index: Index of the support frame used for projection.
            Must be in ``[0, nb_supports - 1]``.  Unused when
            `project` is `False`.  Defaults to ``0``.

    Returns:
        Dict mapping span index (``int``) to coordinate array of shape
        ``(3,)``.
    """
    spans_points, _, _ = self.get_points_for_plot(project, frame_index)
    loads_spans_idx, loads_points_idx = self.span_model.loads_indices
    result_dict: dict = {}
    for index_in_small_array, span_index in enumerate(loads_spans_idx):
        point_index = loads_points_idx[index_in_small_array]
        result_dict[int(span_index)] = spans_points.coords[
            span_index, point_index
        ]
    return result_dict

get_loads_coords_group_points

get_loads_coords_group_points(
    project: bool = False, frame_index: int = 0
) -> dict

Same as get_loads_coords() but uses GroupPoints object

Return a dictionary of load coordinates indexed by span.

If loads exist on spans 0 and 2, the result looks like: {0: [x0, y0, z0], 2: [x2, y2, z2]}.

Parameters:

Name	Type	Description	Default
project	bool	True to project all objects into a support frame (for 2-D graphs). Defaults to False.	False
frame_index	int	Index of the support frame used for projection. Must be in [0, nb_supports - 1]. Unused when project is False. Defaults to 0.	0

Returns:

Type	Description
dict	Dict mapping span index (int) to coordinate array of shape
dict	(3,).

Source code in src/mechaphlowers/core/geometry/position_engine.py

def get_loads_coords_group_points(
    self, project: bool = False, frame_index: int = 0
) -> dict:
    """Same as get_loads_coords() but uses GroupPoints object

    Return a dictionary of load coordinates indexed by span.

    If loads exist on spans 0 and 2, the result looks like:
    ``{0: [x0, y0, z0], 2: [x2, y2, z2]}``.

    Args:
        project: ``True`` to project all objects into a support frame
            (for 2-D graphs). Defaults to ``False``.
        frame_index: Index of the support frame used for projection.
            Must be in ``[0, nb_supports - 1]``.  Unused when
            `project` is `False`.  Defaults to ``0``.

    Returns:
        Dict mapping span index (``int``) to coordinate array of shape
        ``(3,)``.
    """
    group_points = self.get_group_points()
    if project:
        group_points = group_points.change_frame(frame_index)
    spans_points = group_points.get_all_objects_dict()["spans"]
    loads_spans_idx, loads_points_idx = self.span_model.loads_indices
    result_dict: dict = {}
    for index_in_small_array, span_index in enumerate(loads_spans_idx):
        point_index = loads_points_idx[index_in_small_array]
        result_dict[int(span_index)] = spans_points.coords[
            span_index, point_index
        ]
    return result_dict

get_obstacles_points

get_obstacles_points() -> ndarray

Return obstacle coordinates transformed to the section frame.

Source code in src/mechaphlowers/core/geometry/position_engine.py

def get_obstacles_points(self) -> np.ndarray:
    """Return obstacle coordinates transformed to the section frame."""
    return self.coords_calculator.compute_obstacle_coords().points(True)

get_points_for_plot

get_points_for_plot(
    project: bool = False, frame_index: int = 0
) -> tuple[Points, Points, Points]

Return Points objects for spans, supports, and insulators.

Parameters:

Name	Type	Description	Default
project	bool	True to project into a support frame (2-D mode).	False
frame_index	int	Index of the support frame for projection.	0

Returns:

Type	Description
tuple[Points, Points, Points]	Tuple of (spans, supports, insulators) as Points.

Raises:

Type	Description
ValueError	If frame_index is out of range.

Source code in src/mechaphlowers/core/geometry/position_engine.py

def get_points_for_plot(
    self, project: bool = False, frame_index: int = 0
) -> tuple[Points, Points, Points]:
    """Return `Points` objects for spans, supports, and insulators.

    Args:
        project: `True` to project into a support frame (2-D mode).
        frame_index: Index of the support frame for projection.

    Returns:
        Tuple of ``(spans, supports, insulators)`` as `Points`.

    Raises:
        ValueError: If `frame_index` is out of range.
    """
    return self.coords_calculator.get_points_for_plot(project, frame_index)

get_spans_points

get_spans_points(
    frame: Literal['section', 'localsection', 'cable'],
) -> ndarray

Return span cable points in the requested coordinate frame.

Parameters:

Name	Type	Description	Default
frame	Literal['section', 'localsection', 'cable']	One of "section", "localsection", or "cable".	required

Returns:

Type	Description
ndarray	numpy array of shape (n_points, 3).

Source code in src/mechaphlowers/core/geometry/position_engine.py

def get_spans_points(
    self, frame: Literal["section", "localsection", "cable"]
) -> np.ndarray:
    """Return span cable points in the requested coordinate frame.

    Args:
        frame: One of ``"section"``, ``"localsection"``, or ``"cable"``.

    Returns:
        numpy array of shape ``(n_points, 3)``.
    """
    return self.coords_calculator.get_spans(frame).points(True)

get_supports_points

get_supports_points() -> ndarray

Return support structure points (absolute section frame).

Source code in src/mechaphlowers/core/geometry/position_engine.py

def get_supports_points(self) -> np.ndarray:
    """Return support structure points (absolute section frame)."""
    return self.coords_calculator.get_supports().points(True)

initialize_engine

initialize_engine(balance_engine: BalanceEngine) -> None

Initialise internal references from balance_engine.

Source code in src/mechaphlowers/core/geometry/position_engine.py

def initialize_engine(self, balance_engine: BalanceEngine) -> None:
    """Initialise internal references from `balance_engine`."""
    self.span_model = balance_engine.balance_model.nodes_span_model
    self.cable_loads = balance_engine.cable_loads
    self.section_array = balance_engine.section_array
    self.obstacle_array = ObstacleArray.build_empty_array()
    self.coords_calculator = CoordsCalculator(
        section_array=self.section_array,
        span_model=self.span_model,
        cable_loads=self.cable_loads,
        get_displacement=balance_engine.get_displacement,
        obstacle_array=self.obstacle_array,
    )

obstacles_dict

obstacles_dict(project=False, frame_index=0) -> dict

Return obstacle coordinates keyed by obstacle name.

Format: {'obs_0': [[x0, y0, z0], [x1, y1, z1], ...]}.

Source code in src/mechaphlowers/core/geometry/position_engine.py

def obstacles_dict(self, project=False, frame_index=0) -> dict:
    """Return obstacle coordinates keyed by obstacle name.

    Format: ``{'obs_0': [[x0, y0, z0], [x1, y1, z1], ...]}``.
    """
    return self.coords_calculator.obstacles_dict(project, frame_index)

point_distance

point_distance(
    span_index: int, point: ndarray
) -> DistanceResult

Compute the minimum distance from point to a cable span.

Parameters:

Name	Type	Description	Default
span_index	int	Span index in [0, num_supports - 2].	required
point	ndarray	Absolute coordinates of shape (3,).	required

Returns:

Type	Description
DistanceResult	DistanceResult with the distance value and closest-point coordinates.

Raises:

Type	Description
IndexError	If span_index is out of range.
ValueError	If point does not have shape (3,).

Source code in src/mechaphlowers/core/geometry/position_engine.py

def point_distance(
    self, span_index: int, point: np.ndarray
) -> DistanceResult:
    """Compute the minimum distance from `point` to a cable span.

    Args:
        span_index: Span index in ``[0, num_supports - 2]``.
        point: Absolute coordinates of shape ``(3,)``.

    Returns:
        `DistanceResult` with the distance value and closest-point coordinates.

    Raises:
        IndexError: If `span_index` is out of range.
        ValueError: If `point` does not have shape ``(3,)``.
    """
    point = np.asarray(point)
    if point.shape != (3,):
        raise ValueError("point must be a 1D array of shape (3,)")

    ground_supports = self.coords_calculator.supports_ground_coords.copy()
    if span_index < 0 or span_index >= len(ground_supports) - 1:
        raise IndexError(
            f"span_index {span_index} out of range"
            f" [0, {len(ground_supports) - 2}]"
        )

    self.distance_engine.add_span_frame(
        ground_supports[span_index], ground_supports[span_index + 1]
    )
    self.distance_engine.add_curves(
        self.coords_calculator.get_spans(frame="section").coords[
            span_index
        ]
    )
    return self.distance_engine.plane_distance(point, frame="section")

point_relative_to_absolute

point_relative_to_absolute(
    span_index: int, point_relative: ndarray
) -> ndarray

Convert a point from the span-local frame to absolute coordinates.

Span-local frame definition:

• X: along the span direction projected onto the XY plane
• Y: perpendicular to X in the XY plane
• Z: vertical (global Z)

Parameters:

Name	Type	Description	Default
span_index	int	Span index in [0, num_supports - 2].	required
point_relative	ndarray	Coordinate [x, y, z] in the span-local frame.	required

Returns:

Type	Description
ndarray	Absolute coordinate array of shape (3,).

Raises:

Type	Description
IndexError	If span_index is out of range.
ValueError	If point_relative does not have shape (3,).

Source code in src/mechaphlowers/core/geometry/position_engine.py

def point_relative_to_absolute(
    self, span_index: int, point_relative: np.ndarray
) -> np.ndarray:
    """Convert a point from the span-local frame to absolute coordinates.

    Span-local frame definition:

    - X: along the span direction projected onto the XY plane
    - Y: perpendicular to X in the XY plane
    - Z: vertical (global Z)

    Args:
        span_index: Span index in ``[0, num_supports - 2]``.
        point_relative: Coordinate ``[x, y, z]`` in the span-local frame.

    Returns:
        Absolute coordinate array of shape ``(3,)``.

    Raises:
        IndexError: If `span_index` is out of range.
        ValueError: If `point_relative` does not have shape ``(3,)``.
    """
    point_relative = np.asarray(point_relative)
    if point_relative.shape != (3,):
        raise ValueError("point_relative must be a 1D array of shape (3,)")

    ground_supports = self.coords_calculator.supports_ground_coords
    if span_index < 0 or span_index >= len(ground_supports) - 1:
        raise IndexError(
            f"span_index {span_index} out of range"
            f" [0, {len(ground_supports) - 2}]"
        )

    return change_local_frame(
        ground_supports[span_index],
        ground_supports[span_index + 1],
        point_relative,
    )

reset

reset(balance_engine: BalanceEngine) -> None

Reset geometry state from balance_engine.

Called automatically by update when the balance engine notifies; can also be called manually after direct modifications to the section array.

Raises:

Type	Description
TypeError	If balance_engine is not a BalanceEngine.

Source code in src/mechaphlowers/core/geometry/position_engine.py

def reset(self, balance_engine: BalanceEngine) -> None:
    """Reset geometry state from `balance_engine`.

    Called automatically by `update` when the balance engine
    notifies; can also be called manually after direct modifications to
    the section array.

    Raises:
        TypeError: If `balance_engine` is not a `BalanceEngine`.
    """
    if not isinstance(balance_engine, BalanceEngine):
        raise TypeError(
            "balance_engine must be an instance of BalanceEngine"
        )
    if balance_engine.initialized is False:
        self.initialize_engine(balance_engine)
    self.coords_calculator.reset()

update

update(notifier: Notifier) -> None

Observer callback — invoked by BalanceEngine on state change.

Source code in src/mechaphlowers/core/geometry/position_engine.py

def update(self, notifier: Notifier) -> None:
    """Observer callback — invoked by `BalanceEngine` on state change."""
    logger.debug("Position engine notified from balance engine.")
    if isinstance(notifier, BalanceEngine):
        self.reset(balance_engine=notifier)
        # Propagate the notification to any downstream observers (e.g. PlotEngine).
        self.notify()