Field.staggered_vector_access and Field.center_vector for up to 3 index dimensions

pystencils/field.py

@@ -426,13 +426,15 @@ class Field(AbstractField):
         index_shape = self.index_shape
         if len(index_shape) == 0:
             return sp.Matrix([self.center])
-        if len(index_shape) == 1:
+        elif len(index_shape) == 1:
             return sp.Matrix([self(i) for i in range(index_shape[0])])
         elif len(index_shape) == 2:
-            def cb(*args):
-                r = self.__call__(*args)
-                return r
-            return sp.Matrix(*index_shape, cb)
+            return sp.Matrix([[self(i, j) for j in range(index_shape[1])] for i in range(index_shape[0])])
+        elif len(index_shape) == 3:
+            return sp.Matrix([[[self(i, j, k) for k in range(index_shape[2])]
+                             for j in range(index_shape[1])] for i in range(index_shape[0])])
+        else:
+            raise NotImplementedError("center_vector is not implemented for more than 3 index dimensions")
 
     @property
     def center(self):
@@ -534,6 +536,20 @@ class Field(AbstractField):
 
             return prefactor * Field.Access(self, offset, (idx, *index))
 
+    def staggered_vector_access(self, offset):
+        """Like staggered_access, but returns the entire vector/tensor stored at offset."""
+        assert FieldType.is_staggered(self)
+
+        if self.index_dimensions == 1:
+            return sp.Matrix([self.staggered_access(offset)])
+        elif self.index_dimensions == 2:
+            return sp.Matrix([self.staggered_access(offset, i) for i in range(self.index_shape[1])])
+        elif self.index_dimensions == 3:
+            return sp.Matrix([[self.staggered_access(offset, (i, k)) for k in range(self.index_shape[2])]
+                             for i in range(self.index_shape[1])])
+        else:
+            raise NotImplementedError("center_vector is not implemented for more than 3 index dimensions")
+
     @property
     def staggered_stencil(self):
         assert FieldType.is_staggered(self)

pystencils_tests/test_field.py

@@ -28,6 +28,9 @@ def test_field_basic():
     assert neighbor.offsets == (-1, 1)
     assert '_' in neighbor._latex('dummy')
 
+    f = Field.create_fixed_size('f', (8, 8, 2, 2, 2), index_dimensions=3)
+    assert f.center_vector == sp.Matrix([[[f(i, j, k) for k in range(2)] for j in range(2)] for i in range(2)])
+
     f = Field.create_generic('f', spatial_dimensions=5, index_dimensions=2)
     field_access = f[1, -1, 2, -3, 0](1, 0)
     assert field_access.offsets == (1, -1, 2, -3, 0)
@@ -139,12 +142,16 @@ def test_staggered():
     assert j1[0, 2](1) == j1.staggered_access((0, sp.Rational(3, 2)))
     assert j1[0, 1](1) == j1.staggered_access("N")
     assert j1[0, 0](1) == j1.staggered_access("S")
+    assert j1.staggered_vector_access("N") == sp.Matrix([j1.staggered_access("N")])
 
     assert j2[0, 1](1, 1) == j2.staggered_access((0, sp.Rational(1, 2)), 1)
     assert j2[0, 1](1, 1) == j2.staggered_access("N", 1)
+    assert j2.staggered_vector_access("N") == sp.Matrix([j2.staggered_access("N", 0), j2.staggered_access("N", 1)])
 
     assert j3[0, 1](1, 1, 1) == j3.staggered_access((0, sp.Rational(1, 2)), (1, 1))
     assert j3[0, 1](1, 1, 1) == j3.staggered_access("N", (1, 1))
+    assert j3.staggered_vector_access("N") == sp.Matrix([[j3.staggered_access("N", (i, j))
+                                                        for j in range(2)] for i in range(2)])
 
     # D2Q9
     k = ps.fields('k(4) : double[2D]', field_type=FieldType.STAGGERED)