打印清单列表

Question

我正在学习通过设计家族树来制作清单清单。下面是我提出的一种方法，但是在打印结果时遇到麻烦。例如：

如果A有2个孩子，B &ç... 则B有2个孩子，d & E. .. 而C只对孩子，F ...

我会想要打印结果：[A，[B，[D，E]]，[C，[F]]]

希望我的代码有任何改进，关于如何打印上述结果的建议，以图形形式打印。

class FamilyTree: 
    def __init__(self, root): 
     self.name = [root] 
     nmbr = int(input("How many children does " + root + " have?")) 
     if nmbr is not 0: 
      for i, child in enumerate(range(nmbr)): 
       name = input("What is one of " + root + "'s child's name?") 
       setattr(self, "child{0}".format(i), FamilyTree(name)) 
r = print(FamilyTree('A')) 

Answer 1

你可以使用__str__方法，它是通过print()函数调用：

class FamilyTree: 
    def __init__(self, root): 
     self.name = root 
     self.children = [] 
     nmbr = int(input("How many children does " + root + " have? ")) 
     if nmbr is not 0: 
      for i, child in enumerate(range(nmbr)): 
       name = input("What is one of " + root + "'s child's name? ") 
       self.children.append(FamilyTree(name)) 
    def __str__(self): 
     return '[' + self.name + ''.join(', ' + str(c) for c in self.children) + ']' 
r = print(FamilyTree('A')) 

Answer 2

这是从输入和输出拆分对象创建一个好主意。此外，使用setattr将使写入输出更加困难。

这里是一个解决方案，允许您创建一个FamilyTree有或没​​有从用户读取输入：

class FamilyTree: 
    def __init__(self, root, childs = []): 
     self.name = root 
     self.childs = childs 

    def read(self): 
     nmbr = int(input("How many children does " + self.name + " have? ")) 
     if nmbr is not 0: 
      for _ in range(nmbr): 
       name = input("What is one of " + self.name + "'s child's name? ") 
       child = FamilyTree(name) 
       child.read() 
       self.childs.append(child) 

    def __repr__(self): 
     if len(self.childs) == 0: 
      return str("{}".format(self.name)) 
     else: 
      return str("{}, {}".format(self.name, self.childs)) 

# creates a FamilyTree directly so we can test the output 
r = FamilyTree(
     'A', 
     [ 
      FamilyTree(
       'B', 
       [FamilyTree('C'), FamilyTree('C')] 
      ), 
      FamilyTree(
       'C', 
       [FamilyTree('F')] 
      ) 
     ] 
    ) 

# or read input from the user 
# r = FamilyTree('A') 
# r.read() 

print(r) 

输出

A, [B, [C, C], C, [F]]