Getting started

Install

pip install pyvista-frd-reader

Wheels are available for Linux (x86_64 and aarch64), macOS (Intel and Apple silicon), and Windows.

Linux wheels use manylinux_2_28 and require glibc 2.28 or newer. This includes RHEL 8, Debian 10, Ubuntu 20.04, and later releases.

A source build requires CMake and a C++17 compiler. The package has no pure-Python fallback.

Read a file

import pyvista_frd

mesh = pyvista_frd.read("result.frd")
mesh.plot(scalars="STRESS_Mises")

pyvista_frd.read() returns a pyvista.UnstructuredGrid. Nodal results are stored as point data under their CalculiX names. Six-component STRESS and STRAIN arrays also produce _Mises, _sgMises, and _PS1 through _PS3 arrays.

mesh.point_data["original_node_ids"] stores the original FRD node numbers as integers: int32 when every ID fits in the signed 32-bit range, otherwise int64. The width depends on the ID values, not the number of points. Compare IDs numerically, for example mesh.point_data["original_node_ids"] == 42. Earlier versions returned strings and required comparisons against "42".

The first result array is the active scalars. original_node_ids, original_element_ids and set arrays are never active, so a file without results has no active scalars.

mesh.point_data_to_cell_data() can average the numeric nodal results directly. Any averaged node-ID array is metadata with no physical meaning; it does not identify the element. This filter averages existing nodal values and does not recover element integration-point results.

For a file with more than one step, use the reader object:

reader = pyvista_frd.FRDReader("transient.frd")
reader.set_active_time_point(3)
mesh = reader.read()

Write a file

pyvista_frd.write("out_ascii.frd", mesh)
pyvista_frd.write("out_binary.frd", mesh, binary=True)

# Or convert without building a mesh at all.
pyvista_frd.convert("binary.frd", "ascii.frd", binary=False)

What it reads

Supported element types are HE8, PE6, PE15, TE4, HE20, TE10, TR3, TR6, QU4, QU8, BE2, BE3, PY5, and PY13. PY5 and PY13 are the experimental CalculiX pyramid types C3D5 and C3D13. The parser handles short and long fixed-width element records, including records with adjacent node IDs.

The package reads both ASCII encodings and the float32 and float64 binary encodings. CalculiX writes binary FRD for *REFINE MESH and DOUBLE output cards. PyVista’s built-in reader reads ASCII FRD only. See Binary FRD for the record layout and test coverage.

Elements with an invalid node count or an unsupported type produce pyvista.InvalidMeshWarning with the source line number.

Relation to PyVista’s own reader

PyVista already reads ASCII FRD through pyvista.FRDReader. This package is a separate implementation and does not replace PyVista’s reader. External parity results reports the external comparison; Differences from PyVista lists known differences. History and credit records the implementation history and credit.