added class PolygonalChain

freesurfer_surface/__init__.py

@@ -63,6 +63,34 @@ def setlocale(temporary_locale):
 Vertex = collections.namedtuple('Vertex', ['right', 'anterior', 'superior'])
 
 
+class PolygonalChain:
+
+    def __init__(self, vertex_indices: typing.Iterable[int]):
+        self.vertex_indices: typing.Deque[int] = collections.deque(vertex_indices)
+
+    def __eq__(self, other: 'PolygonalChain') -> bool:
+        return self.vertex_indices == other.vertex_indices
+
+    def __repr__(self) -> str:
+        return 'PolygonalChain(vertex_indices={})'.format(tuple(self.vertex_indices))
+
+    def connect(self, other: 'PolygonalChain') -> None:
+        if self.vertex_indices[-1] == other.vertex_indices[0]:
+            self.vertex_indices.pop()
+            self.vertex_indices.extend(other.vertex_indices)
+        elif self.vertex_indices[-1] == other.vertex_indices[-1]:
+            self.vertex_indices.pop()
+            self.vertex_indices.extend(reversed(other.vertex_indices))
+        elif self.vertex_indices[0] == other.vertex_indices[0]:
+            self.vertex_indices.popleft()
+            self.vertex_indices.extendleft(other.vertex_indices)
+        elif self.vertex_indices[0] == other.vertex_indices[-1]:
+            self.vertex_indices.popleft()
+            self.vertex_indices.extendleft(reversed(other.vertex_indices))
+        else:
+            raise ValueError('polygonal chains do not overlap')
+
+
 class _PolygonalCircuit:
 
     _VERTEX_INDICES_TYPE = typing.Tuple[int]

tests/test_polygonal_chain.py

@@ -0,0 +1,59 @@
+import pytest
+
+from freesurfer_surface import PolygonalChain
+
+
+def test_init():
+    chain = PolygonalChain((0, 21, 42, 84))
+    assert tuple(chain.vertex_indices) == (0, 21, 42, 84)
+
+
+def test_reassign_vertex_indices():
+    chain = PolygonalChain((0, 21, 42, 84))
+    chain.vertex_indices = (1, 2, 3, 4)
+    assert tuple(chain.vertex_indices) == (1, 2, 3, 4)
+
+
+def test_eq():
+    assert PolygonalChain((0, 1, 2)) == PolygonalChain((0, 1, 2))
+    # pylint: disable=unneeded-not
+    assert not PolygonalChain((0, 1, 2)) == PolygonalChain((0, 1, 4))
+    assert not PolygonalChain((0, 1, 2)) == PolygonalChain((0, 4, 2))
+    assert not PolygonalChain((0, 1, 2)) == PolygonalChain((4, 1, 2))
+    assert not PolygonalChain((0, 1, 2)) == PolygonalChain((1, 2, 3, 4))
+
+
+def test_repr():
+    assert repr(PolygonalChain([])) \
+        == 'PolygonalChain(vertex_indices=())'
+    assert repr(PolygonalChain((0, 2, 1))) \
+        == 'PolygonalChain(vertex_indices=(0, 2, 1))'
+    assert repr(PolygonalChain((0, 2, 1, 4, 3))) \
+        == 'PolygonalChain(vertex_indices=(0, 2, 1, 4, 3))'
+
+
+@pytest.mark.parametrize(('vertex_indices_a', 'vertex_indices_b', 'expected_vertex_indices'), [
+    ((1, 2, 3), (3, 4), (1, 2, 3, 4)),
+    ((1, 2, 3), (4, 3), (1, 2, 3, 4)),
+    ((3, 2, 1), (3, 4), (4, 3, 2, 1)),
+    ((3, 2, 1), (4, 3), (4, 3, 2, 1)),
+    ((1,), (1,), (1,)),
+    ((1, 2), (1,), (1, 2)),
+    ((1, 2), (2,), (1, 2)),
+    ((0, 3, 1, 5, 2), (3, 5, 2, 0), (3, 5, 2, 0, 3, 1, 5, 2)),
+])
+def test_connect(vertex_indices_a, vertex_indices_b, expected_vertex_indices):
+    chain = PolygonalChain(vertex_indices_a)
+    chain.connect(PolygonalChain(vertex_indices_b))
+    assert PolygonalChain(expected_vertex_indices) == chain
+
+
+@pytest.mark.parametrize(('vertex_indices_a', 'vertex_indices_b'), [
+    ((1, 2, 3), (2, 4)),
+    ((1, 2, 3), ()),
+    ((), (3, 4)),
+])
+def test_connect_fail(vertex_indices_a, vertex_indices_b):
+    chain = PolygonalChain(vertex_indices_a)
+    with pytest.raises(Exception):
+        chain.connect(PolygonalChain(vertex_indices_b))