好像比較懂你的意思了, 試寫了一個 Tree, 不知道你覺得怎麼樣XD
class Tree:
def __init__(self, name):
self.name = name
self.children = {}
def __iter__(self):
return iter(self.children)
def __str__(self):
return self.name
def __repr__(self):
return 'Tree("{}")'.format(self.name)
def relationiter(self):
yield from self.children.items()
def add_child(self, child, relation):
self.children[child] = relation
return child
def dfs(self, include_self=True):
if include_self:
yield self
for child in self.children:
yield child
yield from child.dfs(False)
def bfs(self, include_self=True):
if include_self:
yield self
trees = list(self.children.keys())
while True:
if not trees:
break
tree = trees.pop(0)
yield tree
trees += list(tree.children.keys())
import and create tree:
In [1]: from tree import Tree
In [2]: root = Tree('root')
...:
...: t11 = root.add_child(Tree('t11'), 30)
...: t12 = root.add_child(Tree('t12'), 40)
...:
...: t21 = t11.add_child(Tree('t21'), 15)
...: t22 = t11.add_child(Tree('t22'), 10)
...: t23 = t11.add_child(Tree('t23'), 35)
...:
...: t24 = t12.add_child(Tree('t24'), 20)
...:
測試 __str__ 跟 __repr__:
In [3]: root
Out[3]: Tree("root")
In [4]: print(root)
root
測試 iterator 和 relation iterator:
In [5]: for child in root:
...: print(child)
...:
t12
t11
In [6]: for child, relation in root.relationiter():
...: print(child, relation)
...:
t12 40
t11 30
測試 dfs 和 bfs:
In [7]: for tree in root.dfs(include_self=True):
...: print(tree)
...:
root
t12
t24
t11
t21
t22
t23
In [8]: for tree in root.bfs(include_self=True):
...: print(tree)
...:
root
t12
t11
t24
t21
t22
t23
這邊還有一個問題是, 不知道你原始的資料長甚麼樣子, 所以我無法猜測你怎麼 create tree。
如果是手動一個一個加入 child 的話應該就像上面那樣, create 跟 recursion 沒什麼關係, traverse 的時候才跟 recursion 有關。
除非你有一個對應於 tree 結構的資料, 字典, json 之類的, 然後你想要依資料自動生成, 可能這種情況才會用 recursion 來 build tree。
因為我對於你實際的輸入不是很了解, 但是我猜你想問的是下面這件事情, 我舉個想像的例子說明這一點, 假設我們的原始資料長這樣:
data = {
't11': {
'relation': 30,
'sub': {
't21': {
'relation': 15
},
't22': {
'relation': 10
},
't23': {
'relation': 35
}
}
},
't12': {
'relation': 40,
'sub': {
't24': {
'relation': 20
},
}
}
}
我必須要將這樣子的資料建出一個 Tree 來, 這邊的確就跟 recursion 有關了, 首先我在 Tree 中增加一個 classmethod:
@classmethod
def from_data(cls, name, data):
tree = cls(name)
if data:
for subname, subdata in data.items():
tree.add_child(
cls.from_data(subname, subdata.get('sub', None)),
subdata['relation'])
return tree
接著我可以用下面這種方式 recursive 地 create tree:
root = Tree.from_data('root', data)
測試:
for tree in root.bfs():
print(tree)
for child, relation in tree.relationiter():
print(' {}-{}'.format(child, relation))
結果:
root
t12-40
t11-30
t12
t24-20
t11
t21-15
t23-35
t22-10
t24
t21
t23
t22
P.S. 有問題歡迎討論!
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