A Python module and command line tool for parsing Fortran namelist files

Documentation: http://f90nml.readthedocs.org/en/latest/

f90nml is a Python module and command line tool that provides a simple interface for the reading, writing, and modifying Fortran namelist files.

A namelist file is parsed and converted into an Namelist object, which behaves like a standard Python dict. Values are converted from Fortran data types to equivalent primitive Python types.

The command line tool f90nml can be used to modify individual values inside of a shell environment. It can also be used to convert the data between namelists and other configuration formats. JSON and YAML formats are currently supported.

To read a namelist file sample.nml which contains the following namelists:

&config_nml
   input = 'wind.nc'
   steps = 864
   layout = 8, 16
   visc = 1.0e-4
   use_biharmonic = .false.
/

we would use the following script:

import f90nml
nml = f90nml.read('sample.nml')

which would would point nml to the following dict:

nml = {
    'config_nml': {
        'input': 'wind.nc',
        'steps': 864,
        'layout': [8, 16],
        'visc': 0.0001,
        'use_biharmonic': False
    }
}

File objects can also be used as inputs:

with open('sample.nml') as nml_file:
    nml = f90nml.read(nml_file)

To modify one of the values, say steps, and save the output, just manipulate the nml contents and write to disk using the write function:

nml['config_nml']['steps'] = 432
nml.write('new_sample.nml')

Namelists can also be saved to file objects:

with open('target.nml') as nml_file:
   nml.write(nml_file)

To modify a namelist but preserve its comments and formatting, create a namelist patch and apply it to a target file using the patch function:

patch_nml = {'config_nml': {'visc': 1e-6}}
f90nml.patch('sample.nml', patch_nml, 'new_sample.nml')

A command line tool is provided to manipulate namelist files within the shell:

$ f90nml config.nml -g config_nml -v steps=432

&config_nml
   input = 'wind.nc'
   steps = 432
   layout = 8, 16
   visc = 1.0e-4
   use_biharmonic = .false.
/

See the documentation for details.

f90nml is available on PyPI and can be installed via pip:

$ pip install f90nml

It is also available on Arch Linux via the AUR:

$ git clone https://aur.archlinux.org/python-f90nml.git
$ cd python-f90nml
$ makepkg -sri

f90nml is currently not available on other Linux distributions.

The latest version of f90nml can be installed from source:

$ git clone https://github.com/marshallward/f90nml.git
$ cd f90nml
$ python setup.py install

Users without install privileges can append the --user flag to setup.py:

$ python setup.py install --user