Simple example for reading configuration files.

simple_config.py

'''
This is a simple example of how to read configuration (or parameter) files in Python
using the ConfigParser module.

Docs:
https://docs.python.org/2.7/library/configparser.html
https://docs.python.org/3/library/configparser.html
'''

# Imagine a separate parameter file called "parameters.cfg". Values are grouped into different (named) domains.
# Note strings are not in quotes.
'''
[simulation time]
tot_time = 6
dt = 0.2
time_unit = Gy

[timescales]
tau_df = 3
t_d = 0
t_ia = 2
time_steps = [1, 2, 3, 4, 5]
'''

import ConfigParser
import json

# read the configuration file:
params = ConfigParser.ConfigParser()
params.read("parameters.cfg")

# all values are now in "params"

# access values by domain:
dt = params.get("simulation time", "dt")
time_unit = params.get("simulation time", "time_unit")

# Note that it's ok to have spaces in domain names and keywords

# The ConfigParser doesn't support arrays directly, but they are too useful
# not to have. Instead, we can use a trick by interpreting them as JavaScript strings.
time_steps = json.loads(params.get("timescales", "time_steps"))

# We can use this step to enforce a particular data type:
t_d = float(params.get("timescales", "t_d"))

# For simple datatypes (int, float, boolean) though, there are different "get" methods
# that do the same thing.
t_d = params.getfloat("timescales", "t_d")
t_d = params.getint("timescales", "t_d")