coordinates.mixins.mathops.CoordinateSystemMathMixin.compute_expression#

CoordinateSystemMathMixin.compute_expression(expression: str, coordinates: Sequence[_Buffer | _SupportsArray[dtype[Any]] | _NestedSequence[_SupportsArray[dtype[Any]]] | complex | bytes | str | _NestedSequence[complex | bytes | str]], fixed_axes: Dict[str, float] | None = None) → _Buffer | _SupportsArray[dtype[Any]] | _NestedSequence[_SupportsArray[dtype[Any]]] | complex | bytes | str | _NestedSequence[complex | bytes | str][source]#

Evaluate a named symbolic expression over mixed coordinate inputs.

This method supports evaluating an expression by combining: - Positional *coordinates (1D arrays for free axes), - Keyword fixed_axes (scalars for fixed axes), into a full coordinate list in canonical axis order.

Parameters:

  • expression (str) – The name of the symbolic expression to evaluate.

  • *coordinates (array-like) – Positional coordinate inputs for free axes. The number of entries must match the number of non-fixed axes in the system.

  • fixed_axes (dict of {str: float}, optional) – A dictionary mapping axis names to fixed scalar values (e.g., theta=np.pi/2). These axes must be a subset of the coordinate system’s axes and must not overlap with the axes supplied positionally.

Returns:

The result of evaluating the named expression at the provided coordinates.

Return type:

array-like

Raises:

  • KeyError – If the expression is not found or has no numeric form.

  • ValueError – If coordinate axes or counts are inconsistent with the system definition.

Examples

>>> from pymetric.coordinates import CylindricalCoordinateSystem
>>> from pymetric.utilities.logging import pg_log
>>> pg_log.level = 50
>>> cs = CylindricalCoordinateSystem()
>>> r = np.linspace(0, 1, 100)
>>> z = np.linspace(-1, 1, 100)
>>> R,Z = cs.coordinate_meshgrid(r,z,axes=['rho','z'])
>>> rho = cs.compute_expression_from_coordinates(
...     "metric_density",
...     [R,Z],
...     fixed_axes={"phi": np.pi/4}
... )
>>> rho.shape
(100, 100)