config_example

Example Python program config_example.py

Modules

• import json
• import argparse
• import numpy as np
• import matplotlib
• import matplotlib.pyplot as plt

Methods

• def main(args):

Code

Python example

import json
import argparse

import numpy as np
import matplotlib
import matplotlib.pyplot as plt

matplotlib.rcParams['text.usetex'] = True

# Inspiration came from https://stackoverflow.com/q/3609852/8931942


def main(args):
    # Example taken from matplotlib docs
    # https://matplotlib.org/2.0.2/examples/lines_bars_and_markers/fill_demo.html
    x = np.linspace(0, 1, 500)
    y = np.sin(4 * np.pi * x) * np.exp(-5 * x)

    fig, ax = plt.subplots()

    ax.fill(x, y, zorder=10)
    ax.grid(True, zorder=5)

    if hasattr(args, 'plot_title'):
        plt.title(args.plot_title)
    if hasattr(args, 'x_axis_title'):
        plt.xlabel(args.x_axis_title)
    if hasattr(args, 'y_axis_title'):
        plt.ylabel(args.y_axis_title)

    if hasattr(args, 'plot_name'):
        # extensions = ['.pdf', '.png', '.svg', '.jpg']
        # writing SVG is slow
        extensions = ['.pdf', '.png', '.jpg']
        for extension in extensions:
            plt.savefig(args.plot_name + extension)


if __name__ == '__main__':
    cli_parser = argparse.ArgumentParser(
        description='configuration arguments provided at run time from the CLI'
    )
    cli_parser.add_argument(
        '-c',
        '--config_file',
        dest='config_file',
        type=str,
        default=None,
        help='config file',
    )
    cli_parser.add_argument(
        '-x',
        '--x_axis_title',
        dest='x_axis_title',
        type=str,
        default='',
        help='x-axis name',
    )

    args, unknown = cli_parser.parse_known_args()

    parser = argparse.ArgumentParser(parents=[cli_parser], add_help=False)

    if args.config_file is not None:
        if '.json' in args.config_file:
            # The escaping of "\t" in the config file is necesarry as
            # otherwise Python will try to treat is as the string escape
            # sequence for ASCII Horizontal Tab when it encounters it
            # during json.load
            config = json.load(open(args.config_file))
            parser.set_defaults(**config)

            [
                parser.add_argument(arg)
                for arg in [arg for arg in unknown if arg.startswith('--')]
                if arg.split('--')[-1] in config
            ]

    args = parser.parse_args()

    main(args)

Useful Links

• Articles: https://python-commandments.org/
• Python shell: https://bsdnerds.org/learn-python/
• Tutorial: https://pythonprogramminglanguage.com/