Add option to utilize GPR model to create zero eccentricity initial orbital parameters by vtommasini · Pull Request #12 · sxs-collaboration/SimulationSupport

vtommasini · 2026-08-20T14:37:21Z

Expanded file to allow option of utilizing either PN approximation or a pre-trained GPR model to create zero eccentricity initial orbital parameters. Original PN logic remains unchanged.

method = GPR option: first computes the standard PN baseline for D_0, Omega_0, and adot_0, then applies a correction from a trained GPR model on top of the PN baseline.

currently only works for zero eccentricity GPR; eccentric GPR option is left for a future PR.

runnable both in Python and as a CLI.

…rbital parameters

Copilot

Pull request overview

This PR extends SimulationSupport.EccentricityControl.InitialOrbitalParameters to optionally compute zero-eccentricity initial orbital parameters using a PN baseline plus a Gaussian Process Regression (GPR) correction, and adds a Click-based CLI wrapper for the same functionality.

Changes:

Add method=("PN"|"GPR") and gpr_checkpoints to select PN-only vs. PN+GPR-corrected parameter estimation.
Refactor PN computation into a dedicated helper and add GPR helpers for feature vector assembly and checkpoint-based corrections.
Add a CLI command (initial-orbital-parameters) with text/JSON output.

Suppressed comments (2)

src/SimulationSupport/EccentricityControl/InitialOrbitalParameters.py:429

NotImplementedError is raised with an empty message. Since this is a user-facing code path (selected by method == "GPR" and nonzero eccentricity), it should explain the limitation (e.g. GPR currently supports only zero eccentricity).

    raise NotImplementedError("")

src/SimulationSupport/EccentricityControl/InitialOrbitalParameters.py:161

Spelling typo in the comment (supperted -> supported).

    # Only zero eccentricity is supperted here, since it utilizes ZeroEccParamsFromPN

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+    """Estimate the initial orbital parameters for a BBH evolution.
+
+    Estimates the initial coordinate separation, D_0, orbital angular velocity, Omega_0, and
+    radial expansion velocity, adot_0, from a Post-Newtonian approximation, optionally
+    corrected by a trained Gaussian Process Regression (GPR) model.
+
+    Specify the target eccentricity and either '--separation', '--orbital-angular-velocity',
+    '--num-orbits', or '---time-to-merger'.
+    """
+    orbital_params_specified = [
+        param is not None
+        for param in [
+            separation,
+            orbital_angular_velocity,
+            num_orbits,
+            time_to_merger,
+        ]
+    ]
+    if sum(orbital_params_specified) != 1:
+        raise click.UsageError(
+            "Specify either '--separation', '--orbital-angular-velocity',"
+            "'--num-orbits', or '---time-to-merger'."
+        )


+        if gpr_adot_checkpoint:
+            gpr_checkpoints["adot"] = gpr_adot_checkpoint
+        if not gpr_checkpoints:
+            raise click.UsagError(


nilsvu · 2026-09-02T12:12:19Z

+import click
 import numpy as np
+import rich


Please add these to the requirements

+    from SimulationSupport.gpr import (
+        load_gpr_checkpoint,
+        predict_with_gpr_model,
+    )


+            f"GPR checkpoint expects input feature {missing_feature},"
+            "which is not available. Available features:"
+            f"{sorted(available_values.keys())}. Update the"
+            "'available_values' mapping in this module to match"
+            "the checkpoint's input_features metadata."


+    corrected = {"omega": pn_omega, "adot": pn_adot}
+    for quantity_name, checkpoint_path in gpr_checkpoints.items():
+        if quantity_name not in corrected:
+            raise ValueError(
+                f"Unknown quantity `{quantity_name}` in `gpr_checkpoints`."
+                "Expected one of `D_0`, `Omega_0`, or `adot_0`."
+            )


nilsvu · 2026-09-02T12:11:59Z

    separation: Optional[float] = None,
    orbital_angular_velocity: Optional[float] = None,
    radial_expansion_velocity: Optional[float] = None,
+    method: str = "PN",  # accpets both "PN" and "GPR"


You don't need this comment, it's enough to have it in the docs below

+    help=(
+        "Dimensionless spin vector of the smaller black hole, for example,"
+        "written as '--spin-b 0.0, 0.0, 0.1'."
+    ),


nilsvu

Please add a test that runs the added code. Please also look at the Copilot review and consider the suggestions.

nilsvu · 2026-09-02T12:11:30Z

 ) -> Tuple[float, float, float]:
-    r"""Estimate initial orbital parameters from a Post-Newtonian approximation.
+    r"""Estimate initial orbital parameters from a Post-Newtonian approximation
+    or a Gaussian Process Regression (GPR) correction to the PN approximation.


Please make the first line of the docs fit on one line

nilsvu · 2026-09-02T12:11:59Z

    separation: Optional[float] = None,
    orbital_angular_velocity: Optional[float] = None,
    radial_expansion_velocity: Optional[float] = None,
+    method: str = "PN",  # accpets both "PN" and "GPR"


You don't need this comment, it's enough to have it in the docs below

nilsvu · 2026-09-02T12:12:19Z

+import click
 import numpy as np
+import rich


Please add these to the requirements

nilsvu · 2026-09-02T12:18:07Z

+                gpr_checkpoints=gpr_checkpoints,
+            )
+        else:
+            return _initial_orbital_parameters_gpr_eccentric(


Delete this for now. Just have _initial_orbital_parameters_gpr and assert ecc==0 in it.

nilsvu · 2026-09-02T12:18:53Z

+
+    # Compute the initial orbital parameters from the Post-Newtonian approximation.
+    # Only zero eccentricity is supperted here, since it utilizes ZeroEccParamsFromPN
    assert eccentricity == 0.0, (


Move this assert into the _initial_orbital_parameters_pn function

nilsvu · 2026-09-02T12:19:39Z

+    return pn_separation, orbital_angular_velocity, radial_expansion_velocity
+
+
+def _initial_orbital_parameters_gpr_eccentric(


delete for now

nilsvu · 2026-09-02T12:21:05Z

+
+# CLI
+# The function can be imported and called from Python directly, or it can be called with the CLI.
+def get_initial_orbital_parameters(


You don't need the extra function, move this code into the CLI endpoint function below

nilsvu · 2026-09-02T12:21:59Z

+    if sum(orbital_params_specified) != 1:
+        raise click.UsageError(
+            "Specify either '--separation', '--orbital-angular-velocity',"
+            "'--num-orbits', or '---time-to-merger'."


A lot of this checking is already done in initial_orbital_param. Can you remove some of the redundant checking? Just build the target_params and pass to initial_orbital_param, so the CLI doesn't add much logic (it should be a very thin wrapper around the Python function).

nilsvu · 2026-09-02T12:27:07Z

    return separation, orbital_angular_velocity, radial_expansion_velocity
+
+
+def _build_gpr_feature_vector(input_features, available_values):


This function is only used in 1 place, can you just put the code there?

Add option to utilize GPR model to create zero eccentricity initial o…

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…rbital parameters

Copilot AI lite review requested due to automatic review settings August 20, 2026 14:37

Copilot AI reviewed Aug 20, 2026

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Copilot started reviewing on behalf of vtommasini August 20, 2026 16:50 View session

nilsvu requested changes Sep 2, 2026

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Add option to utilize GPR model to create zero eccentricity initial orbital parameters - #12

Add option to utilize GPR model to create zero eccentricity initial orbital parameters#12
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vtommasini:gpr-initial-orbital-params

vtommasini commented Aug 20, 2026 •

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		return pn_separation, orbital_angular_velocity, radial_expansion_velocity


		def _initial_orbital_parameters_gpr_eccentric(

		return separation, orbital_angular_velocity, radial_expansion_velocity


		def _build_gpr_feature_vector(input_features, available_values):

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vtommasini commented Aug 20, 2026 •

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