8000 Merge pull request #4444 from ianthomas23/4437_qhull_triangle_orienta… · matplotlib/matplotlib@124472d · GitHub
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Merge pull request #4444 from ianthomas23/4437_qhull_triangle_orientation
FIX: Do not correct orientation of triangles returned by Qhull
2 parents 2e445c2 + 44a0206 commit 124472d

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4 files changed

+39
-7
lines changed

4 files changed

+39
-7
lines changed

‎lib/matplotlib/tests/test_triangulation.py

Lines changed: 23 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -985,6 +985,29 @@ def test_trirefiner_fortran_contiguous_triangles():
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assert_array_equal(fine_triang1.triangles, fine_triang2.triangles)
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987987

988+
def test_qhull_triangle_orientation():
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# github issue 4437.
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xi = np.linspace(-2, 2, 100)
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x, y = map(np.ravel, np.meshgrid(xi, xi))
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w = np.logical_and(x > y - 1, np.logical_and(x < -1.95, y > -1.2))
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x, y = x[w], y[w]
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theta = np.radians(25)
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x1 = x*np.cos(theta) - y*np.sin(theta)
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y1 = x*np.sin(theta) + y*np.cos(theta)
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# Calculate Delaunay triangulation using Qhull.
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triang = mtri.Triangulation(x1, y1)
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# Neighbors returned by Qhull.
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qhull_neighbors = triang.neighbors
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# Obtain neighbors using own C++ calculation.
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triang._neighbors = None
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own_neighbors = triang.neighbors
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assert_array_equal(qhull_neighbors, own_neighbors)
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if __name__ == '__main__':
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import nose
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nose.runmodule(argv=['-s', '--with-doctest'], exit=False)

‎lib/matplotlib/tri/_tri.cpp

Lines changed: 9 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -224,7 +224,8 @@ Triangulation::Triangulation(PyArrayObject* x,
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PyArrayObject* triangles,
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PyArrayObject* mask,
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PyArrayObject* edges,
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PyArrayObject* neighbors)
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PyArrayObject* neighbors,
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int correct_triangle_orientations)
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: _npoints(PyArray_DIM(x,0)),
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_ntri(PyArray_DIM(triangles,0)),
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_x(x),
@@ -235,7 +236,8 @@ Triangulation::Triangulation(PyArrayObject* x,
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_neighbors(neighbors)
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{
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_VERBOSE("Triangulation::Triangulation");
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correct_triangles();
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if (correct_triangle_orientations)
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correct_triangles();
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}
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Triangulation::~Triangulation()
@@ -2230,7 +2232,7 @@ TriModule::TriModule()
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Py::Object TriModule::new_triangulation(const Py::Tuple &args)
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{
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_VERBOSE("TriModule::new_triangulation");
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args.verify_length(6);
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args.verify_length(7);
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// x and y.
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PyArrayObject* x = (PyArrayObject*)PyArray_ContiguousFromObject(
@@ -2305,7 +2307,10 @@ Py::Object TriModule::new_triangulation(const Py::Tuple &args)
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}
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}
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2308-
return Py::asObject(new Triangulation(x, y, triangles, mask, edges, neighbors));
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int correct_triangle_orientations = Py::Int(args[6]);
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return Py::asObject(new Triangulation(x, y, triangles, mask, edges, neighbors,
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correct_triangle_orientations));
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}
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Py::Object TriModule::new_tricontourgenerator(const Py::Tuple &args)

‎lib/matplotlib/tri/_tri.h

Lines changed: 6 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -180,13 +180,17 @@ class Triangulation : public Py::PythonExtension<Triangulation>
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* once.
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* neighbors: Optional int array of shape (ntri,3) indicating which
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* triangles are the neighbors of which TriEdges, or -1 if
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* there is no such neighbor. */
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* there is no such neighbor.
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* correct_triangle_orientations: Whether or not should correct triangle
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* orientations so that vertices are
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* ordered anticlockwise. */
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Triangulation(PyArrayObject* x,
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PyArrayObject* y,
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PyArrayObject* triangles,
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PyArrayObject* mask,
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PyArrayObject* edges,
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PyArrayObject* neighbors);
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PyArrayObject* neighbors,
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int correct_triangle_orientations);
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virtual ~Triangulation();
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‎lib/matplotlib/tri/triangulation.py

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -107,7 +107,7 @@ def get_cpp_triangulation(self):
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if self._cpp_triangulation is None:
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self._cpp_triangulation = _tri.Triangulation(
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self.x, self.y, self.triangles, self.mask, self._edges,
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self._neighbors)
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self._neighbors, not self.is_delaunay)
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return self._cpp_triangulation
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def get_masked_triangles(self):

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