PolyData.face_connectivity

property PolyData.face_connectivity: NumpyArray[int]

Return the connectivity array of the polygonal faces.

The connectivity array stores the point ids of every face, one face after another and without any padding. Use face_offsets to determine where each face begins and ends.

Vertices, lines, faces, and strips are held in four separate cell arrays, each with its own offsets and connectivity.

Added in version 0.49.

Returns:

numpy.ndarray

Point ids that define the faces.

Notes

The returned array is read-only and cannot be modified in place. To change the connectivity, assign a new array to this property. The input is copied, so the mesh never aliases an array that may be modified later. To replace the offsets and connectivity together, assign a pyvista.CellArray to faces.

Where that copy is too expensive, assign a pyvista.CellArray built with from_arrays() and deep=False to faces, and keep a reference to the connectivity array. The mesh then wraps that array, so writing to it changes the faces without any copy. Nothing validates the point ids written this way.

Examples

Download Python source code | Download Jupyter notebook

>>> import pyvista as pv
>>> points = pv.Rectangle().points
>>> mesh = pv.PolyData.from_regular_faces(points, [[0, 1, 2], [1, 3, 2]])
>>> mesh.face_connectivity
array([0, 1, 2, 1, 3, 2]...)

The array is read-only and writing to it raises a ValueError.

>>> mesh.face_connectivity.flags['WRITEABLE']
False

Assign a new array instead. Here the winding of both triangles is reversed.

>>> mesh.face_connectivity = [2, 1, 0, 2, 3, 1]
>>> mesh.face_connectivity
array([2, 1, 0, 2, 3, 1]...)

For a mesh large enough that the copy matters, keep the connectivity array and edit it in place.

>>> import numpy as np
>>> connectivity = np.array([0, 1, 2, 1, 3, 2], dtype=pv.ID_TYPE)
>>> mesh.faces = pv.CellArray.from_arrays([0, 3, 6], connectivity, deep=False)
>>> connectivity[:] = [0, 2, 1, 1, 2, 3]
>>> mesh.face_connectivity
array([0, 2, 1, 1, 2, 3]...)

Note that arrays derived from the old topology, such as 'Normals', are not recomputed by either approach and should be removed or regenerated.

See Also

face_offsets

Index into this array at which each face begins.

n_faces

Number of faces.

faces

Faces in the legacy padded format.

vert_connectivity, line_connectivity, strip_connectivity

Connectivity arrays of the other PolyData cell types.

pyvista.UnstructuredGrid.cell_connectivity

Equivalent property for an unstructured grid.

Used In

Docstring Examples

• PolyData.face_offsets (1 use)