Added the ctis.regridding module which can resample spatial-spectral cubes.

ctis/__init__.py

@@ -3,8 +3,10 @@
 spectrograph.
 """
 
+from . import regridding
 from . import scenes
 
 __all__ = [
+    "regridding",
     "scenes",
 ]

ctis/regridding/__init__.py

@@ -0,0 +1,9 @@
+"""
+Resampling routines tailored to work with CTIS observations.
+"""
+
+from ._weights import weights
+
+__all__ = [
+    "weights",
+]

ctis/regridding/_weights.py

@@ -0,0 +1,61 @@
+import numpy as np
+import named_arrays as na
+
+__all__ = [
+    "weights"
+]
+
+
+def weights(
+    wavelength: na.AbstractScalar,
+    position_input: na.AbstractCartesian2dVectorArray,
+    position_output: na.AbstractCartesian2dVectorArray,
+    axis_wavelength: str,
+    axis_position_input: tuple[str, str],
+    axis_position_output: tuple[str, str],
+) -> tuple[na.AbstractScalar, dict[str, int], dict[str, int]]:
+    """
+    A version of :func:`named_arrays.regridding.weights` tailored for use with
+    the spatial-spectral cubes in this package.
+
+    Parameters
+    ----------
+    wavelength
+    position_input
+    position_output
+    axis_wavelength
+    axis_position_input
+    axis_position_output
+    """
+
+    wavelength = wavelength.cell_centers(axis_wavelength)
+    position_input = position_input.cell_centers(axis_wavelength)
+    position_output = position_output.cell_centers(axis_wavelength)
+
+    _weights_2d, shape_input, shape_output = na.regridding.weights(
+        coordinates_input=position_input,
+        coordinates_output=position_output,
+        axis_input=axis_position_input,
+        axis_output=axis_position_output,
+        method="conservative",
+    )
+
+
+def _weights_3d(
+    weights_2d: na.ScalarArray,
+    shape_inputs: dict[str, int],
+    shape_outputs: dict[str, int],
+    axis_wavelength: str,
+) -> tuple[na.AbstractScalar, dict[str, int], dict[str, int]]:
+
+    pass
+
+
+def weights_3d_numpy(
+    weights_2d: np.ndarray,
+    shape_inputs: tuple[int, ...],
+    shape_outputs: tuple[int, ...],
+    axis_wavelength: int,
+) -> tuple[np.ndarray, tuple[int, ...], tuple[int, ...]]:
+
+    pass