Parsing VIC global parameter files in Python

vic_global_options.py

import warnings
from collections import namedtuple, OrderedDict

class Forcing(object):
    def __init__(self, *args, version='4'):
        
        # initialize variables
        self.name = None
        self.path = None
        self.types = []
        if version.startswith('4') or version == '5.0 classic':
            self.format = None
            self.endian = None
            self.year = None
            self.month = None
            self.day = None
        if version.startswith('5'):
            self.steps_per_day = None
        else: 
            self.dt = None
            
        if args:
            self.update(*args)

    def update(self, *args):
        for arg in args:
            if arg[0].startswith('FORCING'):
                self.name = arg[0]
                self.path = arg[1]
            elif arg[0] == 'FORCE_FORMAT':
                self.format = arg[1]
                if self.format == 'BINARY':
                    self._force_type = namedtuple('force_type_binary', ('type', 'sign', 'mult'))
                    self._type_slice = slice(1, 4)
                elif self.format == 'ASCII':
                    self._force_type = namedtuple('force_type_ascii', ('type'))
                    self._type_slice = slice(1, 2)
                else:
                    raise ValueError('Unknown FORCE_FORMAT: %s' % self.format)
            elif arg[0] == 'FORCE_ENDIAN':
                if self.format == 'BINARY':
                    self.endian = arg[1]
                else:
                    warnings.warn('Ignoring FORCE_ENDIAN option since FORCE_FORMAT != BINARY')
            elif arg[0] == 'FORCE_TYPE':
                if self.format == 'BINARY':
                    self.types.append(self._force_type(arg[self._type_slice]))
                if self.format == 'BINARY':
                    self.types.append(self._force_type(arg[self._type_slice]))
            elif arg[0] == 'FORCE_DT':
                self.dt = arg[1]
            elif arg[0] == 'FORCE_STEPS_PER_DAY':
                self.steps_per_day = arg[1]
            elif arg[0] == 'FORCEYEAR':
                self.year = arg[1]
            elif arg[0] == 'FORCEMONTH':
                self.month = arg[1]
            elif arg[0] == 'FORCEDAY':
                self.day = arg[1]
            else:
                raise ValueError('Unknown forcing argument: %s' % arg)
                
    def __repr__(self):
        return 'VIC Forcing Configuration: %s' % self.name


def global_param_options(fname, version='4'):
    
    options = OrderedDict()
    with open(fname, 'r') as f:
        lines = f.readlines()
        for line in lines:
            line = line.strip()  # remove extra whitespace around lines
            if line.startswith('#') or not len(line):
                # line is a comment or is empty
                continue

            # strip trailing comments
            if '#' in line:
                line = line.split(sep='#', maxsplit=1)[0]

            # split the key/value combination
            ops = line.split()
            key = ops[0]
            values = ops[1:]

            if key.startswith('FORCING'):
                forcing_name = key
                options[key] = Forcing(ops, version='4')
            elif not any(key.startswith(s) for s in ['FORCE', 'OUTVAR']):
                options[key] = values
            
    return options
    
# Usage example:
# opts = global_param_options('./samples/global.param.sample.classic.txt', version='5.0 classic')