allow context to be None (#151)

allow outctx to be None

CHANGES.rst

@@ -4,7 +4,12 @@
 Release Notes
 =============
 
-1.15.2 (2025-06-17)
+1.15.3 (unreleased)
+===================
+
+- allow ``context`` to be ``None`` in ``tdriz`` [#151]
+
+1.15.2 (2024-06-17)
 ===================
 
 - build wheels with Numpy 2.0 release candidate [#149]

drizzle/tests/test_drizzle.py

@@ -796,3 +796,39 @@ def test_flux_conservation_distorted(kernel):
         atol=0.0,
         rtol=0.0001,
     )
+
+
+def test_no_context_array():
+    """
+    Test that providing None for "outctx" is supported.
+    """
+    # initialize input:
+    insci = np.ones((200, 400), dtype=np.float32)
+    inwht = np.ones((200, 400), dtype=np.float32)
+    inwht[:, 150:155] = 0
+
+    # initialize output:
+    outsci = np.zeros((210, 410), dtype=np.float32)
+    outwht = np.zeros((210, 410), dtype=np.float32)
+    outctx = None
+
+    # define coordinate mapping:
+    pixmap = np.moveaxis(np.mgrid[1:201, 1:401][::-1], 0, -1)
+
+    # resample:
+    cdrizzle.tdriz(
+        insci, inwht, pixmap,
+        outsci, outwht, outctx,
+        uniqid=1,
+        xmin=0, xmax=400,
+        ymin=0, ymax=200,
+        pixfrac=1,
+        kernel='square',
+        in_units='cps',
+        expscale=1,
+        wtscale=1,
+        fillstr='INDEF',
+    )
+
+    # check that no pixel with 0 weight has any counts:
+    assert np.sum(np.abs(outsci[(outwht == 0)])) == 0.0

src/cdrizzleapi.c

@@ -130,11 +130,13 @@ tdriz(PyObject *obj UNUSED_PARAM, PyObject *args, PyObject *keywords)
     goto _exit;
   }
 
-  con = (PyArrayObject *)PyArray_ContiguousFromAny(ocon, NPY_INT32, 2, 2);
-  if (!con) {
-    driz_error_set_message(&error, "Invalid context array");
-    goto _exit;
-  }
+  if (ocon != Py_None) {
+    con = (PyArrayObject *)PyArray_ContiguousFromAny(ocon, NPY_INT32, 2, 2);
+    if (!con) {
+      driz_error_set_message(&error, "Invalid context array");
+      goto _exit;
+    }
+  };
 
   /* Convert t`he fill value string */