mesh

Lazily loaded mesh from the current reader as a native PyVista object.

In practice, Plotter.mesh is often a pyvista.MultiBlock, especially for *.vtm and time-dependent *.pvd output. That means you usually start by inspecting the block structure, then drill down into the individual datasets inside each block.

Returns

• pyvista.DataSet | pyvista.MultiBlock | None
  • Accessing mesh reads data from the reader and caches it on Plotter.
  • For PVDReader, mesh returns the first block from reader.read().
  • show() and export() reset the cached mesh before rebuilding the scene.

Raises

• ValueError — if no reader is available (call set_file() first).

The examples below were run with:

from pyemsi import Plotter, examples

file_path = examples.transient_path()
plt = Plotter(file_path)
mesh = plt.mesh

For this transient example, mesh is a top-level MultiBlock with block names "1", "3", and "4".

Working With MultiBlock

The most useful first-step operations on a MultiBlock mesh are usually:

• mesh.n_blocks or len(mesh) to see how many top-level blocks exist.
• mesh.keys() to list block names.
• mesh.get_block_name(i) to retrieve the name for a given block index.
• mesh[i] or mesh["name"] to access a child block.
• mesh.bounds to get the overall bounding box of the full composite mesh.

Example:

from pyemsi import Plotter, examples

file_path = examples.transient_path()
plt = Plotter(file_path)
mesh = plt.mesh

print(type(mesh).__name__)  # MultiBlock
print(mesh.n_blocks)  # 3
print(list(mesh.keys()))  # ['1', '3', '4']
print(mesh.get_block_name(0))  # 1
print(mesh.bounds)
# BoundsTuple(x_min = 0.0,
#             x_max = 0.25,
#             y_min = 0.0,
#             y_max = 0.25,
#             z_min = 0.0,
#             z_max = 0.25)

For the transient example above, the top-level MultiBlock already contains leaf datasets, so you can access a block like mesh["1"] directly.

Example:

from pyemsi import Plotter, examples

file_path = examples.transient_path()
plt = Plotter(file_path)
mesh = plt.mesh

block = mesh["1"]
print(type(block).__name__)  # UnstructuredGrid

Inspecting A Leaf Dataset

Once you reach a concrete pyvista.DataSet such as an UnstructuredGrid, the most useful inspection attributes are:

• block.array_names for available scalar/vector arrays.
• block.point_data.keys() for point-data arrays.
• block.cell_data.keys() for cell-data arrays.
• block.n_points and block.n_cells for mesh size.
• block.bounds and block.center for spatial extent.
• block.length for the diagonal length of the dataset bounds.

Example:

from pyemsi import Plotter, examples

file_path = examples.transient_path()
plt = Plotter(file_path)
mesh = plt.mesh
block = mesh["1"]

print(block.array_names)
# ['B-Vec (T)', 'B-Mag (T)', 'vtkOriginalPointIds', 'PropertyID', 'B-Vec (T)', 'B-Mag (T)', 'vtkOriginalCellIds']
print(list(block.point_data.keys()))
# ['B-Vec (T)', 'B-Mag (T)', 'vtkOriginalPointIds']
print(list(block.cell_data.keys()))
# ['PropertyID', 'B-Vec (T)', 'B-Mag (T)', 'vtkOriginalCellIds']
print(block.n_points)  # 396
print(block.n_cells)  # 250
print(block.bounds)
# BoundsTuple(x_min = 0.0,
#             x_max = 0.05000000074505806,
#             y_min = 0.0,
#             y_max = 0.05000000074505806,
#             z_min = 0.0,
#             z_max = 0.10000000149011612)
print(block.center)  # (0.02500000037252903, 0.02500000037252903, 0.05000000074505806)
print(block.length)  # 0.12247448896417099

These attributes are often the quickest way to answer questions like:

• Which field names are available for set_scalar() or set_vector()?
• Which block contains the geometry I care about?
• How large is a block, and where is it located in space?

Common Patterns

Get all top-level block names:

from pyemsi import Plotter, examples

file_path = examples.transient_path()
plt = Plotter(file_path)
mesh = plt.mesh

names = [mesh.get_block_name(i) for i in range(mesh.n_blocks)]
print(names)  # ['1', '3', '4']

Loop over blocks and print useful summary information:

from pyemsi import Plotter, examples

file_path = examples.transient_path()
plt = Plotter(file_path)
mesh = plt.mesh

for block_name in mesh.keys():
    block = mesh[block_name]
    print(block_name, block.n_points, block.n_cells, block.bounds)
    # 1 396 250 BoundsTuple(x_min = 0.0,
    #             x_max = 0.05000000074505806,
    #             y_min = 0.0,
    #             y_max = 0.05000000074505806,
    #             z_min = 0.0,
    #             z_max = 0.10000000149011612)
    # 3 384 225 BoundsTuple(x_min = 0.0,
    #             x_max = 0.10000000149011612,
    #             y_min = 0.0,
    #             y_max = 0.10000000149011612,
    #             z_min = 0.0,
    #             z_max = 0.05000000074505806)
    # 4 2902 2285 BoundsTuple(x_min = 0.0,
    #             x_max = 0.25,
    #             y_min = 0.0,
    #             y_max = 0.25,
    #             z_min = 0.0,
    #             z_max = 0.25)

Find which arrays exist in each block:

from pyemsi import Plotter, examples

file_path = examples.transient_path()
plt = Plotter(file_path)
mesh = plt.mesh

for block_name in mesh.keys():
    block = mesh[block_name]
    print(block_name, block.array_names)
    # 1 ['B-Vec (T)', 'B-Mag (T)', 'vtkOriginalPointIds', 'PropertyID', 'B-Vec (T)', 'B-Mag (T)', 'vtkOriginalCellIds']
    # 3 ['B-Vec (T)', 'B-Mag (T)', 'vtkOriginalPointIds', 'PropertyID', 'B-Vec (T)', 'B-Mag (T)', 'vtkOriginalCellIds']
    # 4 ['B-Vec (T)', 'B-Mag (T)', 'vtkOriginalPointIds', 'PropertyID', 'B-Vec (T)', 'B-Mag (T)', 'vtkOriginalCellIds']

Related Plotter Helpers

If you want the same block names through the Plotter API, use get_block_names(). To hide or show specific blocks in the rendered scene, use set_block_visibility().

Example

from pyemsi import Plotter, examples

file_path = examples.transient_path()
plt = Plotter(file_path)
mesh = plt.mesh

if hasattr(mesh, "keys"):
    print(list(mesh.keys()))  # ['1', '3', '4']

block = mesh["1"]

print(block.array_names)
# ['B-Vec (T)', 'B-Mag (T)', 'vtkOriginalPointIds', 'PropertyID', 'B-Vec (T)', 'B-Mag (T)', 'vtkOriginalCellIds']
print(block.n_points)  # 396
print(block.n_cells)  # 250
print(block.bounds)
# BoundsTuple(x_min = 0.0,
#             x_max = 0.05000000074505806,
#             y_min = 0.0,
#             y_max = 0.05000000074505806,
#             z_min = 0.0,
#             z_max = 0.10000000149011612)