Function _update_nested_dict

lib/matplotlib/style/__init__.py:220–231

Update nested dict (only level of nesting) with new values. Unlike `dict.update`, this assumes that the values of the parent dict are dicts (or dict-like), so you shouldn't replace the nested dict if it already exists. Instead you should update the sub-dict.

(main_dict, new_dict)

def _update_nested_dict(main_dict, new_dict):
    """
    Update nested dict (only level of nesting) with new values.

    Unlike `dict.update`, this assumes that the values of the parent dict are
    dicts (or dict-like), so you shouldn't replace the nested dict if it
    already exists. Instead you should update the sub-dict.
    """
    # update named styles specified by user
    for name, rc_dict in new_dict.items():
        main_dict.setdefault(name, {}).update(rc_dict)
    return main_dict


@_api.deprecated("3.11")