refactor

src/stcal/resample/__init__.py

@@ -1,8 +1,9 @@
 from .resample import *
 
 __all__ = [
-    "LibModelAccess",
+    "LibModelAccessBase",
     "OutputTooLargeError",
     "Resample",
     "resampled_wcs_from_models",
+    "UnsupportedWCSError",
 ]

src/stcal/resample/resample.py

@@ -18,8 +18,8 @@
     interpret_bit_flags,
 )
 
-from .utils import bytes2human, get_tmeasure
-from ..alignment.util import (
+from stcal.resample.utils import bytes2human, get_tmeasure
+from stcal.alignment.util import (
     compute_scale,
     wcs_bbox_from_shape,
     wcs_from_footprints,
@@ -30,10 +30,11 @@
 log.setLevel(logging.DEBUG)
 
 __all__ = [
-    "LibModelAccess",
+    "LibModelAccessBase",
     "OutputTooLargeError",
     "Resample",
     "resampled_wcs_from_models",
+    "UnsupportedWCSError",
 ]
 
 _SUPPORTED_CUSTOM_WCS_PARS = [
@@ -62,7 +63,7 @@ def _resample_range(data_shape, bbox=None):
     return xmin, xmax, ymin, ymax
 
 
-class LibModelAccess(abc.ABC):
+class LibModelAccessBase(abc.ABC):
     # list of model attributes needed by this module. While this is not
     # required, it is helpful for subclasses to check they know how to
     # access these attributes.
@@ -131,8 +132,8 @@ def resampled_wcs_from_models(
     Parameters
     ----------
 
-    input_models : LibModelAccess
-        An object of `LibModelAccess`-derived type.
+    input_models : LibModelAccessBase
+        An object of `LibModelAccessBase`-derived type.
 
     pixel_scale_ratio : float, optional
         Desired pixel scale ratio defined as the ratio of the first model's
@@ -241,6 +242,12 @@ class OutputTooLargeError(RuntimeError):
     """Raised when the output is too large for in-memory instantiation"""
 
 
+class UnsupportedWCSError(RuntimeError):
+    """ Raised when provided output WCS has an unexpected number of axes
+    or has an unsupported structure.
+    """
+
+
 class Resample:
     """
     This is the controlling routine for the resampling process.
@@ -282,9 +289,9 @@ def __init__(self, input_models, pixfrac=1.0, kernel="square",
         """
         Parameters
         ----------
-        input_models : LibModelAccess
-            A `LibModelAccess` object allowing iterating over all contained
-            models of interest.
+        input_models : LibModelAccessBase
+            A `LibModelAccessBase`-based object allowing iterating over
+            all contained models of interest.
 
         kwargs : dict
             Other parameters.
@@ -414,8 +421,8 @@ def check_output_wcs(self, output_wcs, wcs_pars,
         """
         naxes = output_wcs.output_frame.naxes
         if naxes != 2:
-            raise RuntimeError(
-                "Output WCS needs 2 spatial axes but the "
+            raise UnsupportedWCSError(
+                "Output WCS needs 2 coordinate axes but the "
                 f"supplied WCS has {naxes} axes."
             )
 
@@ -841,7 +848,7 @@ def init_resample_variance(self):
             'fillval': np.nan,
             'out_shape': self._output_array_shape,
             # 'exptime': 1.0,
-            'no_ctx': True,
+            'disable_ctx': True,
         }
         self.driz_rnoise = Drizzle(**driz_init_kwargs)
         self.driz_poisson = Drizzle(**driz_init_kwargs)

src/stcal/resample/utils.py

@@ -1,26 +1,62 @@
-import os
-from pathlib import Path, PurePath
+from copy import deepcopy
+import asdf
 
 import numpy as np
 from astropy.nddata.bitmask import interpret_bit_flags
 
 __all__ = [
-    "build_mask", "build_output_model_name", "get_tmeasure", "bytes2human"
+    "build_mask", "get_tmeasure", "bytes2human", "load_custom_wcs"
 ]
 
 
-def build_output_model_name(input_filename_list):
-    fnames = {f for f in input_filename_list if f is not None}
+def load_custom_wcs(asdf_wcs_file, output_shape=None):
+    """ Load a custom output WCS from an ASDF file.
 
-    if not fnames:
-        return "resampled_data_{resample_suffix}{resample_file_ext}"
+    Parameters
+    ----------
+    asdf_wcs_file : str
+        Path to an ASDF file containing a GWCS structure.
+
+    output_shape : tuple of int, optional
+        Array shape (in ``[x, y]`` order) for the output data. If not provided,
+        the custom WCS must specify one of: pixel_shape,
+        array_shape, or bounding_box.
+
+    Returns
+    -------
+    wcs : WCS
+        The output WCS to resample into.
 
-    # TODO: maybe remove ending suffix for single file names?
-    prefix = os.path.commonprefix(
-        [PurePath(f).stem.strip('_- ') for f in fnames]
-    )
+    """
+    if not asdf_wcs_file:
+        return None
+
+    with asdf.open(asdf_wcs_file) as af:
+        wcs = deepcopy(af.tree["wcs"])
+        wcs.pixel_area = af.tree.get("pixel_area", None)
+        wcs.pixel_shape = af.tree.get("pixel_shape", None)
+        wcs.array_shape = af.tree.get("array_shape", None)
+
+    if output_shape is not None:
+        wcs.array_shape = output_shape[::-1]
+        wcs.pixel_shape = output_shape
+    elif wcs.pixel_shape is not None:
+        wcs.array_shape = wcs.pixel_shape[::-1]
+    elif wcs.array_shape is not None:
+        wcs.pixel_shape = wcs.array_shape[::-1]
+    elif wcs.bounding_box is not None:
+        wcs.array_shape = tuple(
+            int(axs[1] + 0.5)
+            for axs in wcs.bounding_box.bounding_box(order="C")
+        )
+    else:
+        raise ValueError(
+            "Step argument 'output_shape' is required when custom WCS "
+            "does not have neither of 'array_shape', 'pixel_shape', or "
+            "'bounding_box' attributes set."
+        )
 
-    return prefix + "{resample_suffix}{resample_file_ext}"
+    return wcs
 
 
 def build_mask(dqarr, bitvalue, flag_name_map=None):