Returns the indices of the x, y (and z) boundary cells.
This property returns the indices of the cells on the x, y (and z) boundaries, respectively. Note that each axis direction will have both a lower and upper boundary. The property will return the indices corresponding to the lower and upper boundaries separately.
E.g. for a 2D domain, there are 2 x-boundaries and 2 y-boundaries (4 in total). In this case, the return is a list of length 4 organized [ind_Bx1, ind_Bx2, ind_By1, ind_By2]:
By2 + ------------- + | | | | Bx1 | | Bx2 | | | | + ------------- + By1
Here, we construct a small 2D tree mesh and return the indices of the x and y-boundary cells.
>>> from discretize import TreeMesh >>> import numpy as np >>> import matplotlib.pyplot as plt
>>> hx = np.ones(16) >>> hy = np.ones(16) >>> mesh = TreeMesh([hx, hy]) >>> mesh.refine_ball([4.0,4.0], [4.0], ) >>> ind_Bx1, ind_Bx2, ind_By1, ind_By2 = mesh.cell_boundary_indices
>>> ax = plt.subplot(111) >>> mesh.plot_grid(ax=ax) >>> ax.scatter(*mesh.cell_centers[ind_Bx1].T) >>> plt.show()