Getting started

Install

pip install pyvista-frd-reader

Wheels are published for Linux (x86_64 and aarch64), macOS (Intel and Apple silicon) and Windows. They carry a compiled library and no CPython extension module, so one wheel per platform serves every supported interpreter.

The Linux wheels are manylinux_2_28 – glibc 2.28 or newer, so RHEL 8, Debian 10, Ubuntu 20.04 and later. That floor comes from NumPy and VTK rather than from this package: the core needs only C++17, but a wheel tagged for an older glibc than its dependencies can be installed alongside would be promising something that does not work.

Installing from source needs CMake and a C++17 compiler. There is no pure-Python fallback, deliberately: a reader that silently falls back is indistinguishable from one that works until someone measures it.

Read a file

import pyvista_frd

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

pyvista_frd.read() returns a pyvista.UnstructuredGrid. Every nodal result in the file is attached as point data under the name CalculiX gave it, and for any six-component STRESS or STRAIN array five derived arrays are appended – _Mises, _sgMises, and _PS1 through _PS3.

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.frd", mesh)               # ASCII
pyvista_frd.write("out.frd", mesh, binary=True)  # about a third of the size

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

What it reads

Element types HE8, PE6, PE15, TE4, HE20, TE10, TR3, TR6, QU4, QU8, BE2, BE3, PY5 and PY13 – the last two being CalculiX’s experimental pyramids, C3D5 and C3D13. Both the short and long element-record formats are handled, including the case CalculiX produces past 9,999 nodes where the node ids in a record run together with no separator at all.

All four encodings, which is a block header’s last field: the two ASCII widths and the two binary ones. Binary FRD is what CalculiX writes from *REFINE MESH and from a DOUBLE output card, and PyVista’s own reader cannot open it – it parses FRD as text, so a binary file yields an empty mesh or an error. Binary FRD covers how that decode is checked.

Elements with the wrong number of nodes, or a type nothing recognises, raise pyvista.InvalidMeshWarning naming the line they were found on.

Relation to PyVista’s own reader

PyVista reads .frd already, through pyvista.FRDReader. This package reimplements that reader rather than replacing it, and is graded against it: The external parity sweep records a comparison over 1,766 files nobody here wrote, and Where this reader differs from PyVista’s lists every place the two deliberately differ, with the test that pins each one.

Both are Rafal’s design. Where this work came from says whose work this is.