Python - 用字典列表中的第 K 个索引值替换值
给定一个字典列表，任务是编写一个Python程序，如果键的值是列表，则用值的第 k 个索引替换特定键的值。
例子：
Input : test_list = [{‘gfg’ : [5, 7, 9, 1], ‘is’ : 8, ‘good’ : 10}, {‘gfg’ : 1, ‘for’ : 10, ‘geeks’ : 9}, {‘love’ : 3, ‘gfg’ : [7, 3, 9, 1]}], K = 2, key = “gfg”
Output : [{‘gfg’: 9, ‘is’: 8, ‘good’: 10}, {‘gfg’: 1, ‘for’: 10, ‘geeks’: 9}, {‘love’: 3, ‘gfg’: 9}]
Explanation : gfg is assigned with 9 which is 2nd index in list.
Input : test_list = [{‘gfg’ : [5, 7, 9, 1], ‘is’ : 8, ‘good’ : 10}, {‘gfg’ : 1, ‘for’ : 10, ‘geeks’ : 9}], K = 2, key = “gfg”
Output : [{‘gfg’: 9, ‘is’: 8, ‘good’: 10}, {‘gfg’: 1, ‘for’: 10, ‘geeks’: 9}]
Explanation : gfg is assigned with 9 which is 2nd index in list.
方法 #1：使用循环 + isinstance()
在这里，我们使用 isinstance() 来检查值的列表类型，并使用循环来遍历字典。
Python3
# Python3 code to demonstrate working of
# Replace value by Kth index value in Dictionary List
# Using loop + isinstance()
# initializing list
test_list = [{'gfg': [5, 7, 9, 1], 'is': 8, 'good': 10},
{'gfg': 1, 'for': 10, 'geeks': 9},
{'love': 3, 'gfg': [7, 3, 9, 1]}]
# printing original list
print("The original list is : " + str(test_list))
# initializing K
K = 2
# initializing Key
key = "gfg"
for sub in test_list:
# using isinstance() to check for list
if isinstance(sub[key], list):
sub[key] = sub[key][K]
# printing result
print("The Modified Dictionaries : " + str(test_list))Python3
# Python3 code to demonstrate working of
# Replace value by Kth index value in Dictionary List
# Using dictionary comprehension + isinstance()
# initializing list
test_list = [{'gfg': [5, 7, 9, 1], 'is': 8, 'good': 10},
{'gfg': 1, 'for': 10, 'geeks': 9},
{'love': 3, 'gfg': [7, 3, 9, 1]}]
# printing original list
print("The original list is : " + str(test_list))
# initializing K
K = 2
# initializing Key
key = "gfg"
# intermediate Dictionaries constructed using dictionary comprehension
res = [{newkey: (val[K] if isinstance(val, list) and newkey == key else val)
for newkey, val in sub.items()} for sub in test_list]
# printing result
print("The Modified Dictionaries : " + str(res))输出：
The original list is : [{‘gfg’: [5, 7, 9, 1], ‘is’: 8, ‘good’: 10}, {‘gfg’: 1, ‘for’: 10, ‘geeks’: 9}, {‘love’: 3, ‘gfg’: [7, 3, 9, 1]}]
The Modified Dictionaries : [{‘gfg’: 9, ‘is’: 8, ‘good’: 10}, {‘gfg’: 1, ‘for’: 10, ‘geeks’: 9}, {‘love’: 3, ‘gfg’: 9}]
方法#2：使用字典理解+ isinstance()
在此，我们使用 isinstance() 使用修改后的字典值重建字典，并使用字典理解来形成中间字典。
蟒蛇3
# Python3 code to demonstrate working of
# Replace value by Kth index value in Dictionary List
# Using dictionary comprehension + isinstance()
# initializing list
test_list = [{'gfg': [5, 7, 9, 1], 'is': 8, 'good': 10},
{'gfg': 1, 'for': 10, 'geeks': 9},
{'love': 3, 'gfg': [7, 3, 9, 1]}]
# printing original list
print("The original list is : " + str(test_list))
# initializing K
K = 2
# initializing Key
key = "gfg"
# intermediate Dictionaries constructed using dictionary comprehension
res = [{newkey: (val[K] if isinstance(val, list) and newkey == key else val)
for newkey, val in sub.items()} for sub in test_list]
# printing result
print("The Modified Dictionaries : " + str(res))
输出：
The original list is : [{‘gfg’: [5, 7, 9, 1], ‘is’: 8, ‘good’: 10}, {‘gfg’: 1, ‘for’: 10, ‘geeks’: 9}, {‘love’: 3, ‘gfg’: [7, 3, 9, 1]}]
The Modified Dictionaries : [{‘gfg’: 9, ‘is’: 8, ‘good’: 10}, {‘gfg’: 1, ‘for’: 10, ‘geeks’: 9}, {‘love’: 3, ‘gfg’: 9}]