數學與蟒蛇幾個列表

Question

我試着去獲得蟒三種不同的列出所有可能的組合

說我有三個列表

A = [2,3,4,7,9] 
B = [2,3,5] 
C = [1,2] 

我想回到所有組合的是真實的[ 1] + B [J] -C [K] == 3

D = [[i,j,k] for i in A for j in B for k in C] 

這給了我所有的組合以列表格式，但如何從這裏下去？

Answer 1

您可以使用itertools.product的列表理解來檢查每個組合以查看它是否符合您的條件。

>>> from itertools import product 
>>> [(a,b,c) for a,b,c in product(A,B,C) if a + b - c == 3] 
[(2, 2, 1), (2, 3, 2), (3, 2, 2)] 

Answer 2

只是在末尾添加的條件：

>>> D = [[i,j,k] for i in A for j in B for k in C if i + j - k == 3] 
>>> D 
[[2, 2, 1], [2, 3, 2], [3, 2, 2]] 

Answer 3

只需添加if i+j-k == 3。您不需要A[i]等，因爲該索引每個list，而i,j和k已經是元素本身。

D = [[i,j,k] for i in A for j in B for k in C if i+j-k == 3] 

你也應該考慮itertools.product避免嵌套這樣的：

import itertools 
D = [[i,j,k] for i,j,k in itertools.product(A, B, C) if i+j-k == 3]