# Examples from pyvista.DataSet.find_closest_cell
# ===============================================

# Find nearest cell on a sphere centered on the
# origin to the point `[0.1, 0.2, 0.3]`.
import pyvista as pv
mesh = pv.Sphere()
point = [0.1, 0.2, 0.3]
index = mesh.find_closest_cell(point)
index

# Make sure that this cell indeed is the closest to
# `[0.1, 0.2, 0.3]`.
import numpy as np
cell_centers = mesh.cell_centers()
relative_position = cell_centers.points - point
distance = np.linalg.norm(relative_position, axis=1)
np.argmin(distance)

# Find the nearest cells to several random points that
# are centered on the origin.
points = 2 * np.random.default_rng().random((5000, 3)) - 1
indices = mesh.find_closest_cell(points)
indices.shape

# For the closest cell, find the point inside the cell that is
# closest to the supplied point.  The rectangle is a unit square
# with 1 cell and 4 nodal points at the corners in the plane with
# `z` normal and `z=0`.  The closest point inside the cell is
# not usually at a nodal point.
unit_square = pv.Rectangle()
index, closest_point = unit_square.find_closest_cell(
    [0.25, 0.25, 0.5], return_closest_point=True
)
closest_point

# But, the closest point can be a nodal point, although the index of
# that point is not returned.  If the closest nodal point by index is
# desired, see `DataSet.find_closest_point()`.
index, closest_point = unit_square.find_closest_cell(
    [1.0, 1.0, 0.5], return_closest_point=True
)
closest_point

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