From da97b7dfc255aab6c97355aae33550e36021dbad Mon Sep 17 00:00:00 2001
From: Roy Smart <roytsmart@gmail.com>
Date: Tue, 22 Apr 2025 23:46:38 -0600
Subject: [PATCH 1/2] Added the `ctis.regridding` module which can resample
 spatial-spectral cubes.

---
 ctis/__init__.py            |  2 ++
 ctis/regridding/__init__.py |  9 ++++++++
 ctis/regridding/_weights.py | 44 +++++++++++++++++++++++++++++++++++++
 3 files changed, 55 insertions(+)
 create mode 100644 ctis/regridding/__init__.py
 create mode 100644 ctis/regridding/_weights.py

diff --git a/ctis/__init__.py b/ctis/__init__.py
index 8107466..53a6aa8 100644
--- a/ctis/__init__.py
+++ b/ctis/__init__.py
@@ -3,8 +3,10 @@
 spectrograph.
 """
 
+from . import regridding
 from . import scenes
 
 __all__ = [
+    "regridding",
     "scenes",
 ]
diff --git a/ctis/regridding/__init__.py b/ctis/regridding/__init__.py
new file mode 100644
index 0000000..b931a3b
--- /dev/null
+++ b/ctis/regridding/__init__.py
@@ -0,0 +1,9 @@
+"""
+Resampling routines tailored to work with CTIS observations.
+"""
+
+from ._weights import weights
+
+__all__ = [
+    "weights",
+]
diff --git a/ctis/regridding/_weights.py b/ctis/regridding/_weights.py
new file mode 100644
index 0000000..60b44a5
--- /dev/null
+++ b/ctis/regridding/_weights.py
@@ -0,0 +1,44 @@
+from typing import Sequence
+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.weights` targeted for use with
+    the spatial-spectral cubes used 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, 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",
+    )
+
+

From 16c18f7ad385645ea09438e34e6c31d6778d7df5 Mon Sep 17 00:00:00 2001
From: Roy Smart <roytsmart@gmail.com>
Date: Wed, 23 Apr 2025 08:09:54 -0600
Subject: [PATCH 2/2] prototypes

---
 ctis/regridding/_weights.py | 27 ++++++++++++++++++++++-----
 1 file changed, 22 insertions(+), 5 deletions(-)

diff --git a/ctis/regridding/_weights.py b/ctis/regridding/_weights.py
index 60b44a5..78c6137 100644
--- a/ctis/regridding/_weights.py
+++ b/ctis/regridding/_weights.py
@@ -1,8 +1,7 @@
-from typing import Sequence
+import numpy as np
 import named_arrays as na
 
 __all__ = [
-
     "weights"
 ]
 
@@ -16,8 +15,8 @@ def weights(
     axis_position_output: tuple[str, str],
 ) -> tuple[na.AbstractScalar, dict[str, int], dict[str, int]]:
     """
-    A version of :func:`named_arrays.weights` targeted for use with
-    the spatial-spectral cubes used in this package.
+    A version of :func:`named_arrays.regridding.weights` tailored for use with
+    the spatial-spectral cubes in this package.
 
     Parameters
     ----------
@@ -33,7 +32,7 @@ def weights(
     position_input = position_input.cell_centers(axis_wavelength)
     position_output = position_output.cell_centers(axis_wavelength)
 
-    _weights, shape_input, shape_output = na.regridding.weights(
+    _weights_2d, shape_input, shape_output = na.regridding.weights(
         coordinates_input=position_input,
         coordinates_output=position_output,
         axis_input=axis_position_input,
@@ -42,3 +41,21 @@ def weights(
     )
 
 
+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