Diff dict function

diff_dict.py

def compare_dicts(old_dict, new_dict):
    diff_items = {}
    for key, value in old_dict.items():
        if isinstance(value, dict):
            result = compare_dicts(value,
                new_dict[key] if key in new_dict and isinstance(new_dict[key], dict) else {})
            diff_items.update(
                {'{}.{}'.format(key, sub_key): value for sub_key, value in result.items()})
        elif key not in new_dict or value != new_dict[key]:
            diff_items[key] = value
    return diff_items


def format_one_dict(prefix, dict_data):
    return '\n'.join(['{} {} {}'.format(prefix, key, value) for key, value in dict_data.items()])


def repr_diff_dict(old_dict, new_dict):
    return '{}\n{}'.format(format_one_dict('-', old_dict), format_one_dict('+', new_dict))


def diff_dict(old_dict, new_dict):
    return repr_diff_dict(compare_dicts(old_dict, new_dict), compare_dicts(new_dict, old_dict))


# Usage
# >>> old_dict = {'a': 10, 'c': {'x': 11, 'z': {'e': 20}}, 'b': 15}
# >>> new_dict = {'e': 30, 'c': 66}
# >>> print(diff_dict(old_dict, new_dict))
# - a 10
# - c.x 11
# - c.z.e 20
# - b 15
# + e 30
# + c 66