, что далеко от дерева, но как об этом
import copy
mydata = {1000024: [[0.7, [1000022, 11, -12]], [0.3, [1000022, 2, -1]]],
1000021: [[0.6, [1000024, 1, -2]], [0.4, [1000022, 21]]]}
def prob_tree(data,ini,prob=1):
data=copy.deepcopy(data)
val=data.pop(ini,None)
if val:
for lst in val:
if lst[1][0] in data:
extra=lst[1][1:]
for x in data[lst[1][0]]:
x[1].extend(extra)
prob_tree(data,lst[1][0],lst[0])
else:
print(prob*lst[0],lst[1])
prob_tree(mydata,1000021)
выход
0.42 [1000022, 11, -12, 1, -2]
0.18 [1000022, 2, -1, 1, -2]
0.4 [1000022, 21]
EDIT
В вдохновение ударил и использование небольшого функционального стиля здесь новая версия
import itertools, functools
def partition(pred, iterable):
'Use a predicate to partition entries into false entries and true entries'
# partition(is_odd, range(10)) --> 0 2 4 6 8 and 1 3 5 7 9
# Direct from the recipes in itertools documentation
t1, t2 = itertools.tee(iterable)
return itertools.filterfalse(pred, t1), filter(pred, t2)
def prob_tree(data,ini) -> (float,tuple):
"""Generator of all end points of the probability tree contained
in data, starting with ini"""
for prob,path in data[ini]:
no_more,more = map(tuple,partition(lambda x: x in data, path))
if more:
for node in itertools.product(*[prob_tree(data,x) for x in more]):
new_prob,new_path = functools.reduce(lambda acum,new: (acum[0]*new[0],acum[1]+new[1]),node,(prob,tuple()))
yield new_prob, no_more + new_path
else:
yield prob, no_more
mydata = {1: [[.9, [2,3]], [.1, [4,5]]],
4: [[.2, [6,7]], [.5, [8,9]], [.3, [10,11,12]]],
5: [[.4, [13,14]], [.6, [15,16]]]
}
mydata2 = {1: [[.8, [2,3]], [.1, [4,5]],[.05, [2,4]],[.05,[5,6]] ],
4: [[.2, [6,7]], [.5, [8,9]], [.3, [10,11,12]]],
5: [[.4, [13,14]], [.6, [15,16]]]
}
mydata3 = {1: [[.8, [2,3]], [.1, [4,5]],[.05, [2,4]],[.05,[5,6]] ],
4: [[.2, [6,7]], [.5, [8,9]], [.3, [10,11,12]]],
5: [[.4, [13,14]], [.6, [15,16]]],
13:[[.58,[23,32]],[.42,[42]] ],
16:[ [.9,[17,18]], [.1,[20,21]] ],
}
выход
>>> for x in prob_tree(mydata,1):
print(x)
(0.9, (2, 3))
(0.008000000000000002, (6, 7, 13, 14))
(0.012000000000000002, (6, 7, 15, 16))
(0.020000000000000004, (8, 9, 13, 14))
(0.03, (8, 9, 15, 16))
(0.012, (10, 11, 12, 13, 14))
(0.018, (10, 11, 12, 15, 16))
>>>
>>>
>>> for x in prob_tree(mydata2,1):
print(x)
(0.8, (2, 3))
(0.008000000000000002, (6, 7, 13, 14))
(0.012000000000000002, (6, 7, 15, 16))
(0.020000000000000004, (8, 9, 13, 14))
(0.03, (8, 9, 15, 16))
(0.012, (10, 11, 12, 13, 14))
(0.018, (10, 11, 12, 15, 16))
(0.010000000000000002, (2, 6, 7))
(0.025, (2, 8, 9))
(0.015, (2, 10, 11, 12))
(0.020000000000000004, (6, 13, 14))
(0.03, (6, 15, 16))
>>>
>>>
>>>
>>> for x in prob_tree(mydata3,1):
print(x)
(0.8, (2, 3))
(0.004640000000000001, (6, 7, 14, 23, 32))
(0.003360000000000001, (6, 7, 14, 42))
(0.010800000000000002, (6, 7, 15, 17, 18))
(0.0012000000000000001, (6, 7, 15, 20, 21))
(0.0116, (8, 9, 14, 23, 32))
(0.008400000000000001, (8, 9, 14, 42))
(0.027000000000000003, (8, 9, 15, 17, 18))
(0.003, (8, 9, 15, 20, 21))
(0.006959999999999999, (10, 11, 12, 14, 23, 32))
(0.00504, (10, 11, 12, 14, 42))
(0.0162, (10, 11, 12, 15, 17, 18))
(0.0018, (10, 11, 12, 15, 20, 21))
(0.010000000000000002, (2, 6, 7))
(0.025, (2, 8, 9))
(0.015, (2, 10, 11, 12))
(0.0116, (6, 14, 23, 32))
(0.008400000000000001, (6, 14, 42))
(0.027000000000000003, (6, 15, 17, 18))
(0.003, (6, 15, 20, 21))
>>>
EDIT 2 добавления проверки циклических ссылок
def prob_tree_with_check(data,ini,visited=frozenset()):
"""Generator of all end points of the probability tree contained
in data, starting with ini. Check if a previously visited branch
of the tree is visited again and raise RuntimeError in that case"""
if ini in visited:
raise RuntimeError("Branch allready visited: %r"%ini)
visited = visited.union((ini,))
for prob,path in data[ini]:
no_more,more = map(tuple,partition(lambda x: x in data,path))
if more:
for node in itertools.product(*[prob_tree_with_check(data,x,visited) for x in more]):
new_prob,new_path = functools.reduce(lambda acum,new: (acum[0]*new[0],acum[1]+new[1]),node,(prob,tuple()))
yield new_prob, no_more + new_path
else:
yield prob, no_more
mydata_bad = {1: [[.9, [2,3]], [.1, [4,5]]],
4: [[.2, [6,7]], [.5, [8,9]], [.3, [10,11,12]]],
5: [[.4, [13,14]], [.6, [15,16,1]]] # <-- try to go back to 1
}
выход
>>> for x in prob_tree_with_check(mydata_bad,1):
x
(0.9, (2, 3))
Traceback (most recent call last):
File "<pyshell#35>", line 1, in <module>
for x in prob_tree_with_check(mydata_bad,1):
File "C:\Users\David\Documents\Python Scripts\stackoverflow_test.py", line 137, in prob_tree_with_check
for node in itertools.product(*[prob_tree_with_check(data,x,visited) for x in more]):
File "C:\Users\David\Documents\Python Scripts\stackoverflow_test.py", line 137, in prob_tree_with_check
for node in itertools.product(*[prob_tree_with_check(data,x,visited) for x in more]):
File "C:\Users\David\Documents\Python Scripts\stackoverflow_test.py", line 132, in prob_tree_with_check
raise RuntimeError("Branch already visited: %r"%ini)
RuntimeError: Branch already visited: 1
>>>
, которые не похожи на дерево мне ... – Copperfield
Существует гораздо более простой способ, чем ответ, если у меня было время, чтобы написать демо-код: Фенвик деревья. Они полезны для префиксных сумм, которые, как я думаю, вы ищете. Кроме того, вставка нового значения в дерево Fenwick и обновление соответствующей суммы префикса составляет ~ 4 строки кода. Если сегодня у меня будет время позже, я постараюсь опубликовать код для вас. –
@ScottM Я посмотрел на деревья Фенвика, и это может быть то, что я ищу. Я не понимаю их достаточно хорошо, чтобы быть уверенным, хотя. Я был бы признателен, если бы у вас было время показать мне простой пример. – pfnuesel