![](/img/trans.png)
[英]parent->child relationships in appengine python (bigtable)
[英]Python: Calculating the Path from Parent Child Relationships
父項)作為CSV(700,000行)輸入
Child Parent
fA00 f0
fA9 fA0
fA31 fA0
fA30 fA0
fA1 fA00
dccfA1 fA00
fA2 fA00
fA3 fA00
fA01 fA00
fA4 fA00
fA5 fA00
fA6 fA00
fA7 fA00
fA0 fA00
fA142149 fA00
fA02 fA00
fA8 fA00
qA1 fA10
fA22 fA10
fA23 fA10
fA11 fA10
qA2 fA10
fA15 fA11
fA13 fA11
fA12 fA11
fA14 fA13
fA17 fA16
fA18 fA17
fA19 fA17
fA20 fA17
fA21 fA19
etc....
它上升到14個深度。 父級最高的是f0
我想遍歷子父母關系以確定路徑
預期結果
f0 --- top
f0\fa00
f0\fa00\.Child
f0\fa00\.Child2etc
f0\fA0
f0\fA0\.Child
f0\fA0\.Child2etc
如何在Python中執行此操作?
我開始思考復雜的樹結構遞歸構造,但是基本上它很簡單。 創建子項到父項的映射,然后從子項列表開始,列出其父項,然后從父項的父項到頂部。 遞歸例程很容易提取孩子的祖先。
'''
This is the family tree:
------------------------
f0:
a0:
b0
b1:
b2:
a1:
b3:
b4:
a2:
b5:
c0
c1
'''
ancestry = [
('b1', 'a0'),
('c1', 'b5'),
('b2', 'a0'),
('b3', 'a1'),
('b4', 'a1'),
('b5', 'a2'),
('a0', 'f0'),
('a1', 'f0'),
('a2', 'f0'),
('b0', 'a0'),
('c0', 'b5'),
]
代碼是:
parents = set()
children = {}
for c,p in ancestry:
parents.add(p)
children[c] = p
# recursively determine parents until child has no parent
def ancestors(p):
return (ancestors(children[p]) if p in children else []) + [p]
# for each child that has no children print the geneology
for k in (set(children.keys()) - parents):
print '/'.join(ancestors(k))
輸出為:
f0/a1/b4
f0/a0/b0
f0/a0/b1
f0/a0/b2
f0/a1/b3
f0/a2/b5/c1
f0/a2/b5/c0
我將其作為練習來閱讀csv文件 ,並可能對輸出進行更好的排序。
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.