Added iris.sg.effective_area() function. (#13)

iris/__init__.py

@@ -4,10 +4,12 @@
 
 from . import planning
 from . import data
+from . import response
 from . import sg
 
 __all__ = [
     "planning",
     "data",
+    "response",
     "sg",
 ]

iris/response/__init__.py

@@ -0,0 +1,9 @@
+"""
+The IRIS instrument response files.
+"""
+
+from ._response import files
+
+__all__ = [
+    "files",
+]

iris/response/_response.py

@@ -0,0 +1,17 @@
+import pathlib
+
+__all__ = [
+    "files",
+]
+
+
+def files() -> list[pathlib.Path]:
+    """
+    A list of the IDL ``.sav`` files storing the IRIS instrument response.
+    """
+
+    directory = pathlib.Path(__file__).parent
+
+    result = sorted(directory.glob("*.geny"))
+
+    return result

iris/response/_response_test.py

@@ -0,0 +1,9 @@
+import pathlib
+import iris
+
+
+def test_files():
+    result = iris.response.files()
+    assert len(result) > 0
+    for r in result:
+        assert isinstance(r, pathlib.Path)

iris/sg/__init__.py

@@ -3,9 +3,11 @@
 """
 
 from . import background
+from ._effective_area import effective_area
 from ._spectrograph import SpectrographObservation
 
 __all__ = [
     "background",
+    "effective_area",
     "SpectrographObservation",
 ]

iris/sg/_effective_area.py

@@ -0,0 +1,81 @@
+import scipy.io
+import astropy.units as u
+import named_arrays as na
+import iris
+
+__all__ = [
+    "effective_area",
+]
+
+
+def effective_area(wavelength: u.Quantity | na.AbstractScalar) -> na.AbstractScalar:
+    """
+    Load the effective area of the spectrograph.
+
+    Currently only Version 1 is implemented.
+
+    Parameters
+    ----------
+    wavelength
+        The wavelength of the incident light at which to evaluate the effective
+        area.
+
+    Examples
+    --------
+
+    Plot the effective area of the spectrograph as a function of wavelength.
+
+    .. jupyter-execute::
+
+        import matplotlib.pyplot as plt
+        import astropy.units as u
+        import astropy.visualization
+        import named_arrays as na
+        import iris
+
+        # Define a wavelength grid
+        wavelength = na.linspace(
+            start=1250 * u.AA,
+            stop=3000 * u.AA,
+            axis="wavelength",
+            num=1001,
+        )
+
+        # Compute the effective area
+        area = iris.sg.effective_area(wavelength)
+
+        # Plot the effective area as a function of wavelength
+        with astropy.visualization.quantity_support():
+            fig, ax = plt.subplots()
+            na.plt.plot(
+                wavelength,
+                area,
+            )
+            ax.set_xlabel(f"wavelength ({ax.get_xlabel()})")
+            ax.set_ylabel(f"effective area ({ax.get_ylabel()})")
+
+    """
+
+    files = iris.response.files()
+
+    file_v1 = files[0]
+
+    struct_v1 = scipy.io.readsav(file_v1)["p0"]
+
+    wavelength_v1 = struct_v1["LAMBDA"][0] * u.nm
+    area_v1 = struct_v1["AREA_SG"][0] * u.cm**2
+
+    axis = "_dummy"
+    axes = ("channel", axis)
+
+    axis = "_dummy"
+
+    wavelength_v1 = na.ScalarArray(wavelength_v1, axes=axis)
+    area_v1 = na.ScalarArray(area_v1, axes=axes).sum("channel")
+
+    return na.interp(
+        x=wavelength,
+        xp=wavelength_v1,
+        fp=area_v1,
+        axis=axis,
+    )

iris/sg/_effective_area_test.py

@@ -0,0 +1,19 @@
+import pytest
+import astropy.units as u
+import named_arrays as na
+import iris
+
+
+@pytest.mark.parametrize(
+    argnames="wavelength",
+    argvalues=[
+        1330 * u.AA,
+        na.linspace(1300, 1400, axis="w", num=11) * u.AA,
+    ],
+)
+def test_effective_area(
+    wavelength: u.Quantity | na.AbstractScalar,
+):
+    result = iris.sg.effective_area(wavelength)
+
+    assert result.sum() > 0 * u.cm**2