Converter for CalculiX FRD files

Date:	2022-10-01
tags:	CalculiX, Python
Author:	Roland Smith

On several occasions, the author has written small scripts to extract data from CalculiX's FRD files and manipulate them in some way.

Having done that quick and dirty several times, the author decided to do this properly and write software that could read all the node-related data from an FRD file and save it in formats that are easy for programming languages to read.

The frdconvert software is written in Python, so it supports converting to Python's native pickle format. But json and sqlite3 output are also supported. The latter two should be readable by many programming languages.

frdconvert has been written so that it can be used as a Python module and as a standalone program. It uses only modules from the Python standard library.

Usage as a module

import frdconvert as frd

data = frdconvert.read_frd("test/job.frd")
frdconvert.write_sqlite(data, "test/job.db")

The data is a dictionary with the keys being the names of the sections present in the FRD-file. The possible names of the sections are listed in NODE_RELATED near the top of frdconvert.py. Each of the values in data is again a dictionary. The values in these underlying dictionaries are tuples of float. The keys are the number of the node that the tuple belong to. Note that node numbers do not have to start at 1!

Usage as a standalone program

This program is meant to be used from a terminal (POSIX operating system) or cmd-window (ms-windows). In the examples below > represents the command-prompt.

Converting an frd file to json:

> frdconvert.py -j --log=info test/job.frd
INFO: file “test/job.frd” contains 365432 lines.
INFO: extracting NODES
INFO: extracting DISP
INFO: extracting MESTRAIN
INFO: extracting FORC
INFO: extracting ZZSTR
INFO: writing JSON file “test/job.json”

Showing the online help:

> frdconvert.py -h
usage: frdconvert.py [-h] (-j | -p | -s) [-l] [-v] [--log {debug,info,warning,error}] [file ...]

Extract the node-related data from a CalculiX FRD file and save it in formats suitable for use with
programming languages. Currently supports JSON, sqlite3 and pickle (for Python) output formats.

positional arguments:
file                  one or more files to process

optional arguments:
-h, --help            show this help message and exit
-j, --json            save FRD file contents in JSON format
-p, --pickle          save FRD file contents in pickle format
-s, --sqlite          save FRD file contents in sqlite3 database format
-l, --license         print the license
-v, --version         show program's version number and exit
--log {debug,info,warning,error}
                        logging level (defaults to 'warning')