This package provides an interface for handling the MIXD mesh format developed at CATS. Routines for reading/writing big endian binary files and a Mixd class for reading meshes and associated data are provided.

Installation

In your python environment run:

pip install mixdpy

Examples

Some examples:

Write and read binaries

import mixdpy
import numpy as np

arr = np.arange(24, dtype=np.int32).reshape(2, 3, 4)
filename = "somebinarray"

mixdpy.write_int(filename, arr, shift=False)
out = mixdpy.read_int(filename, shape=(3, 4), shift=False)

Reading a mesh

import mixdpy

path_to_mesh = "mesh"

mesh = mixdpy.Mixd(path_to_mesh, minf_name="minf.space") # Infers dpst flag from mien entries

# Read associated data
ndf = mesh.nsd + 1
ins_data_out = mesh.read_node_float("data.out",entry_shape=(ndf,))
ins_data_all = mesh.read_node_float("data.all",entry_shape=(ndf,),nts=-1)

print(mesh.get_bounds())

Export mesh using meshio

import mixdpy
import meshio

path_to_mesh = "mesh"
mesh = mixdpy.Mixd(path_to_mesh)

ndf = mesh.nsd + 1
ins_data_out = mesh.read_node_float("data.out",entry_shape=(ndf,))

export_mesh = meshio.Mesh(
    mesh.mxyz,
    {mesh.get_meshio_elem():mesh.mien},
    point_data = {
        "velocity" : ins_data_out[0,:,:mesh.nsd],
        "pressure" : ins_data_out[0,:,mesh.nsd]
    }
)
export_mesh.write("ins.vtk")

Visualize partitioning with pyvista

import pyvista as pv
import mixdpy
import numpy as np

path_to_mesh = "tests/meshes/hypermesh2mixd_sd"
mesh = mixdpy.Mixd(path_to_mesh)
pv_cell_type = pv.CellType.TRIANGLE
n_part = 4

# Pad mesh array with 0s if necessary
coords = np.pad(mesh.mxyz, (0, 3-mesh.nsd))

# Read mipe array from mesh path (nrec, ne, 1). If nrec is 1 the dimension is NOT collapsed.
partitioning_array = mesh.read_elem_int(mesh.path / f"mipe.{n_part:04d}")

out_mesh = pv.UnstructuredGrid({pv_cell_type:mesh.mien}, coords)

out_mesh.cell_data[f"Partitoning {n_part}"] = partitioning_array[0] 

out_mesh.plot(show_edges=True)