1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
|
"""
.. _point_cell_scalars_example:
Point Cell Scalars
~~~~~~~~~~~~~~~~~~
This example demonstrates how to add point scalars for each individual cell to
a dataset.
"""
from __future__ import annotations
import numpy as np
from pyvista import examples
# %%
# load the first 4 cells from the example UnstructuredGrid. Note how the number
# of points is less than 32 since all the points are joined in the center.
grid = examples.load_hexbeam().extract_cells(range(4))
grid
# %%
# Plot Point Scalars
# ~~~~~~~~~~~~~~~~~~
# At this point it's possible to assign only point or cell scalars to this
# dataset. First, let's just plot some simple point scalars.
grid.point_data['Point Data'] = range(grid.n_points)
grid.plot(scalars='Point Data')
# %%
# Plot Cell Scalars
# ~~~~~~~~~~~~~~~~~
# Next, let's plot cell scalars. We're simply assigning based on the cell
# index.
grid.cell_data['Cell Data'] = range(grid.n_cells)
grid.plot(scalars='Cell Data')
# %%
# Splitting the Cells
# ~~~~~~~~~~~~~~~~~~~
# If you wanted to assign data to each point of each cell and plot that, it's
# simply not possible since these hexahedral cells all share the same
# points. To split up individual cells, separate them using
# :func:`pyvista.DataSetFilters.separate_cells`.
#
# With this filter the resulting :class:`pyvista.UnstructuredGrid` now contains
# 32 points, or 8 for each cell. They are now fully separated with no shared
# points.
split_cells = grid.separate_cells()
split_cells
# %%
# Plot Point Cell Data
# ~~~~~~~~~~~~~~~~~~~~
# Now we can plot values for each point for each cell. This will still be
# assigned to the point data.
#
# Here we use :func:`numpy.hstack` for clarity, but as long as the length of
# the data matches the number of points, you'll be able to use this approach.
#
# See how the plotted values appear continuous within a cell and discontinuous
# between cells. This matches how stresses and strains are calculated from
# finite element solutions.
split_cells.point_data['Point Cell Data'] = np.hstack(
(
np.linspace(0, 8, 8), # cell 0
np.linspace(0, 12, 8), # cell 1
np.linspace(0, 16, 8), # cell 2
np.linspace(0, 20, 8), # cell 3
),
)
split_cells.plot(scalars='Point Cell Data')
|
