Python：家庭级

Question

我使用参数name，title和children来实现一个＆＃34; person＆＃34; -class。 功能＆＃34; desc＆＃34;应该返回家谱下面的人员名单。

到目前为止，我已经做到了这一点：

class Person():
    def __init__(self, name, title, children=None):
        self.name = name
        self.title = title
        if children is None:
            self.children = []
        else:
            self.children = children


    def desc(self):
        self.out = []
        if self.children:
            for kid in self.children:
                self.out.append(kid)
            return self.out


p1 = Person("p1", "test")
p2 = Person("p2", "test", children = [p1])
p3 = Person("p3", "test")
p4 = Person("p4", "test", children = [p2, p3])
p5 = Person("p5", "boss", children = [p4])
print [person.title for person in p5.desc()]
# desired output:
# ['test', 'test', 'test','test']
print [person.name for person in p5.desc()]
# desired output:
# ['p4', 'p2', 'p1', 'p3']

但是我的实际输出看起来不像想要的那样。 所以，我的问题是：你如何拯救孩子？在一个简单的清单？问题显然在def desc（）中。 谢谢你的帮助！

Answer 1

您必须递归children列表：

def desc(self):
    out = []
    for kid in self.children:
        out.append(kid)
        out.extend(kid.desc())
    return out

这在当前对象上使用desc()方法，然后在每个列出的子节点上调用相同的方法来扩展当前结果列表。这种情况一直持续到遇到没有孩子的物体为止。

请注意，out不需要是实例的属性;我改为保留了一个局部变量。

这会产生您的预期输出：

>>> class Person():
...     def __init__(self, name, title, children=None):
...         self.name = name
...         self.title = title
...         if children is None:
...             self.children = []
...         else:
...             self.children = children
...     def desc(self):
...         out = []
...         for kid in self.children:
...             out.append(kid)
...             out.extend(kid.desc())
...         return out
... 
>>> p1 = Person("p1", "test")
>>> p2 = Person("p2", "test", children = [p1])
>>> p3 = Person("p3", "test")
>>> p4 = Person("p4", "test", children = [p2, p3])
>>> p5 = Person("p5", "boss", children = [p4])
>>> print [person.title for person in p5.desc()]
['test', 'test', 'test', 'test']
>>> print [person.name for person in p5.desc()]
['p4', 'p2', 'p1', 'p3']

因此p5.desc()将p4添加到out列表，然后使用p4.desc()的结果扩展列表。 p4.desc()将p2添加到其本地out列表中，使用p2.desc()的结果进行扩展，然后将p3添加到out并使用p3.desc()等扩展它