python - 在 Python 中打印树数据结构

Question

我正在寻找一种可能的树打印实现，它以用户友好的方式打印树，而不是作为对象的实例。

我在网上遇到了这个解决方案:

来源:http://cbio.ufs.ac.za/live_docs/nbn_tut/trees.html

class node(object):
    def __init__(self, value, children = []):
        self.value = value
        self.children = children

    def __repr__(self, level=0):
        ret = "\t"*level+repr(self.value)+"\n"
        for child in self.children:
            ret += child.__repr__(level+1)
        return ret

此代码以下列方式打印树:

'grandmother'
    'daughter'
        'granddaughter'
        'grandson'
    'son'
        'granddaughter'
        'grandson'

是否可以在不改变 __repr__ 方法的情况下获得相同的结果，因为我将它用于其他目的。

编辑:

不修改__repr__和__str__

的解决方案

def other_name(self, level=0):
    print '\t' * level + repr(self.value)
    for child in self.children:
        child.other_name(level+1)

Answer 1

是的，将 __repr__ 代码移动到 __str__，然后在树上调用 str() 或将其传递给 print 语句。记得在递归调用中也使用 __str__:

class node(object):
    def __init__(self, value, children = []):
        self.value = value
        self.children = children

    def __str__(self, level=0):
        ret = "\t"*level+repr(self.value)+"\n"
        for child in self.children:
            ret += child.__str__(level+1)
        return ret

    def __repr__(self):
        return '<tree node representation>'

演示:

>>> root = node('grandmother')
>>> root.children = [node('daughter'), node('son')]
>>> root.children[0].children = [node('granddaughter'), node('grandson')]
>>> root.children[1].children = [node('granddaughter'), node('grandson')]
>>> root
<tree node representation>
>>> str(root)
"'grandmother'\n\t'daughter'\n\t\t'granddaughter'\n\t\t'grandson'\n\t'son'\n\t\t'granddaughter'\n\t\t'grandson'\n"
>>> print root
'grandmother'
    'daughter'
        'granddaughter'
        'grandson'
    'son'
        'granddaughter'
        'grandson'