Add access to field decay values in SimulationData

Co-authored-by: greptile-apps[bot] <165735046+greptile-apps[bot]@users.noreply.github.com>

Author: marco-rudolph-inside

CHANGELOG.md

@@ -7,6 +7,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+- Access field decay values in `SimulationData` via `sim_data.field_decay` as `TimeDataArray`.
+
 ### Changed
 - By default, batch downloads will skip files that already exist locally. To force re-downloading and replace existing files, pass the `replace_existing=True` argument to `Batch.load()`, `Batch.download()`, or `BatchData.load()`.
 - The `BatchData.load_sim_data()` function now overwrites any previously downloaded simulation files (instead of skipping them).

tests/test_data/test_sim_data.py

@@ -229,6 +229,38 @@ def test_final_decay():
     assert dv == 0.11
 
 
+def test_field_decay_array():
+    sim_data = make_sim_data()
+    log_extended = (
+        sim_data.log + "\n- Time step   1392 / time 1.33e-13s ( 19 % done), field decay: 6.58e-01"
+    )
+    sim_data = sim_data.copy(update={"log": log_extended})
+
+    fd = sim_data.field_decay
+    steps = fd.coords["t"].values
+    decay_values = fd.values
+
+    assert len(fd) == 2
+    assert int(steps[0]) == 827
+    assert int(steps[1]) == 1392
+    assert float(decay_values[0]) == 0.11
+    assert float(decay_values[1]) == 0.658
+
+
+def test_decay_missing_in_log():
+    sim_data = make_sim_data()
+    sim_data = sim_data.copy(update={"log": "no regex matches in this log"})
+    dv = sim_data.final_decay_value
+    assert dv == 1.0
+
+
+def test_field_decay_log_none():
+    sim_data = make_sim_data()
+    sim_data = sim_data.copy(update={"log": None})
+    with pytest.raises(DataError):
+        _ = sim_data.field_decay
+
+
 def test_to_dict():
     sim_data = make_sim_data()
     j = sim_data.dict()

tidy3d/components/data/sim_data.py

@@ -4,6 +4,7 @@
 
 import json
 import pathlib
+import re
 from abc import ABC
 from collections import defaultdict
 from typing import Callable, Optional, Union
@@ -14,7 +15,7 @@
 import xarray as xr
 
 from tidy3d.components.autograd.utils import split_list
-from tidy3d.components.base import JSON_TAG, Tidy3dBaseModel
+from tidy3d.components.base import JSON_TAG, Tidy3dBaseModel, cached_property
 from tidy3d.components.base_sim.data.sim_data import AbstractSimulationData
 from tidy3d.components.file_util import replace_values
 from tidy3d.components.monitor import Monitor
@@ -29,7 +30,7 @@
 from tidy3d.exceptions import DataError, FileError, Tidy3dKeyError
 from tidy3d.log import log
 
-from .data_array import FreqDataArray
+from .data_array import FreqDataArray, TimeDataArray
 from .monitor_data import AbstractFieldData, FieldTimeData, MonitorDataType, MonitorDataTypes
 
 DATA_TYPE_MAP = {data.__fields__["monitor"].type_: data for data in MonitorDataTypes}
@@ -931,21 +932,29 @@ class SimulationData(AbstractYeeGridSimulationData):
         description="A boolean flag denoting whether the simulation run diverged.",
     )
 
-    @property
-    def final_decay_value(self) -> float:
-        """Returns value of the field decay at the final time step."""
+    @cached_property
+    def field_decay(self) -> TimeDataArray:
+        """Returns a TimeDataArray of field decay values over time steps."""
         log_str = self.log
         if log_str is None:
             raise DataError(
-                "No log string in the SimulationData object, can't find final decay value."
+                "No log string in the SimulationData object, can't extract field decay."
             )
-        lines = log_str.split("\n")
-        decay_lines = [line for line in lines if "field decay" in line]
-        final_decay = 1.0
-        if len(decay_lines) > 0:
-            final_decay_line = decay_lines[-1]
-            final_decay = float(final_decay_line.split("field decay: ")[-1])
-        return final_decay
+
+        matches = re.findall(r"- Time step\s+(\d+)\s+/.*?field decay:\s*([0-9.eE+-]+)", log_str)
+
+        steps = [int(m[0]) for m in matches]
+        decays = [float(m[1]) for m in matches]
+        return TimeDataArray(decays, coords={"t": steps})
+
+    @property
+    def final_decay_value(self) -> float:
+        """Returns value of the field decay at the final time step."""
+        field_decay = self.field_decay
+        if len(field_decay) == 0:
+            log.warning("No field decay values found, using 1.0 as final decay value.")
+            return 1.0
+        return float(field_decay.values[-1])
 
     def source_spectrum(self, source_index: int) -> Callable:
         """Get a spectrum normalization function for a given source index."""