Python – 将单项字典分组为列表值

给定单项字典列表，根据相似值将它们分组到字典值列表中。

Input : [{“Gfg” : 3}, {“is”: 8}, {“Gfg”: 18}, {“Best”: 33}]
Output : {‘Gfg’: [3, 18], ‘is’: [8], ‘Best’: [33]}
Explanation : Each key converted to list values and dictionary.

Input : [{“Gfg” : 3}, {“Gfg”: 8}, {“Gfg”: 18}, {“Best”: 33}]
Output : {‘Gfg’: [3, 18, 8], ‘Best’: [33]}
Explanation : Each key converted to list values and dictionary.

方法 #1：使用 setdefault() + 循环

这是可以执行此任务的粗暴方式。在此，我们使用循环遍历所有字典值，并使用 setdefault() 为公共键分配其对应的分组值列表。

Python3

# Python3 code to demonstrate working of 
# Group single item dictionaries into List values
# Using setdefault() + loop
  
# initializing lists
test_list = [{"Gfg" : 3}, {"is": 8}, {"Best": 10}, {"Gfg": 18}, {"Best": 33}]
  
# printing original list
print("The original list : " + str(test_list))
  
res = {}
  
# using loop to loop through each dictionary
for idx in test_list:
      
    # items() to extract item
    for key, val in idx.items():
          
        # setdefault performs task of setting empty list value as default
        res.setdefault(key, []).append(val)
  
# printing result 
print("The constructed dictionary : " + str(res))

输出

The original list : [{'Gfg': 3}, {'is': 8}, {'Best': 10}, {'Gfg': 18}, {'Best': 33}]
The constructed dictionary : {'Gfg': [3, 18], 'is': [8], 'Best': [10, 33]}

方法 #2：使用 defaultdict() + *运算符+ 循环

这是可以执行此任务的另一种方式。在此，我们使用 defaultdict() 进行空列表初始化。 *运算符用于解包字典项，循环用于遍历字典。

Python3

# Python3 code to demonstrate working of 
# Group single item dictionaries into List values
# Using defaultdict() + * operator + loop
from collections import defaultdict
  
# initializing lists
test_list = [{"Gfg" : 3}, {"is": 8}, {"Best": 10}, {"Gfg": 18}, {"Best": 33}]
  
# printing original list
print("The original list : " + str(test_list))
  
res = defaultdict(list)
for ele in test_list:
      
    # using * operator to unpack
    # reducing one loop
    key, val = tuple(*ele.items())
    res[key].append(val)
  
# printing result 
print("The constructed dictionary : " + str(dict(res)))

输出

The original list : [{'Gfg': 3}, {'is': 8}, {'Best': 10}, {'Gfg': 18}, {'Best': 33}]
The constructed dictionary : {'Gfg': [3, 18], 'is': [8], 'Best': [10, 33]}