Python – 从元组列表中分配对元素

给定一个元组列表，分配给每个元素，它的对元素来自其他相似的对。

Input : test_list = [(5, 3), (7, 5), (8, 4)]
Output : {5: [3], 7: [5], 8: [4], 4: []}
Explanation : 1st elements are paired with respective 2nd elements from all tuples.

Input : test_list = [(5, 3)]
Output : {5: [3]}
Explanation : Only one tuples, 5 paired with 3.

方法：使用 setdefault() + 循环

在此，我们使用暴力方法来解决这个问题，对每个元组进行迭代，并将每个键和值的默认值设置为空列表，如果已经存在，则将元素附加到相应的列表中。

Python3

# Python3 code to demonstrate working of 
# Assign pair elements from Tuple Lists
# Using setdefault + loop
  
# initializing list
test_list = [(5, 3), (7, 5), (2, 7), (3, 8), (8, 4)]
  
# printing string
print("The original list : " + str(test_list))
  
# initializing dictionary
res = dict()
for key, val in test_list:
      
    # adding to both, corresponding keys and values
    res.setdefault(val, [])
    res.setdefault(key, []).append(val)
  
# printing results 
print("The resultant pairings : " + str(res))

输出

The original list : [(5, 3), (7, 5), (2, 7), (3, 8), (8, 4)]
The resultant pairings : {3: [8], 5: [3], 7: [5], 2: [7], 8: [4], 4: []}