如何从已有的字典中有选择地创建一个字典？

original_dict = {'a': 1, 'b': 2, 'c': 3, 'd': 4}
selected_keys = ['a', 'c']

new_dict = {key: original_dict[key] for key in selected_keys if key in original_dict}
print(new_dict)  # 输出: {'a': 1, 'c': 3}

original_dict = {'a': 1, 'b': 2, 'c': 3, 'd': 4}
selected_keys = ['a', 'c']

new_dict = dict((key, original_dict[key]) for key in selected_keys)
print(new_dict)  # 输出: {'a': 1, 'c': 3}

original_dict = {'a': 1, 'b': 2, 'c': 3, 'd': 4}

def condition(item):
    return item[0] in ['a', 'c']  # 只选择键为'a'或'c'的项

new_dict = dict(filter(condition, original_dict.items()))
print(new_dict)  # 输出: {'a': 1, 'c': 3}