Python – 提取 List 中每个 Nth 元组的 Kth 元素

给定元组列表，提取每个第 N 个元组的第 K 个列元素。

Input :test_list = [(4, 5, 3), (3, 4, 7), (4, 3, 2), (4, 7, 8), (6, 4, 7), (2, 5, 7), (1, 9, 10), (3, 5, 7)], K = 2, N = 3
Output : [3, 8, 10]
Explanation : From 0th, 3rd, and 6th tuple, 2nd elements are 3, 8, 10.

Input :test_list = [(4, 5, 3), (3, 4, 7), (4, 3, 2), (4, 7, 8), (6, 4, 7), (2, 5, 7), (1, 9, 10), (3, 5, 7)], K = 0, N = 3
Output : [4, 4, 1]
Explanation : From 0th, 3rd, and 6th tuple, 0th elements are 4, 4, 1.

方法#1：使用循环

在此，我们通过使用 range() 的第三个参数跳过 N 个值进行迭代，并使用循环将每个 Kth 值附加到列表中。

Python3

# Python3 code to demonstrate working of 
# Extract Kth element of every Nth tuple in List
# Using loop
  
# initializing list
test_list = [(4, 5, 3), (3, 4, 7), (4, 3, 2), (4, 7, 8),
             (6, 4, 7), (2, 5, 7), (1, 9, 10), (3, 5, 7)]
  
# printing original list
print("The original list is : " + str(test_list))
  
# initializing K
K = 1
  
# initializing N 
N = 3
  
res = []
for idx in range(0, len(test_list), N):
      
    # extract Kth element
    res.append(test_list[idx][K])
  
# printing result 
print("The extracted elements : " + str(res))

输出

The original list is : [(4, 5, 3), (3, 4, 7), (4, 3, 2), (4, 7, 8), (6, 4, 7), (2, 5, 7), (1, 9, 10), (3, 5, 7)]
The extracted elements : [5, 7, 9]

方法#2：使用列表推导

在此，我们使用与上述相同的方法，使用列表理解使用单线执行提取元素的任务。

Python3

# Python3 code to demonstrate working of 
# Extract Kth element of every Nth tuple in List
# Using list comprehension
  
# initializing list
test_list = [(4, 5, 3), (3, 4, 7), (4, 3, 2), (4, 7, 8),
             (6, 4, 7), (2, 5, 7), (1, 9, 10), (3, 5, 7)]
  
# printing original list
print("The original list is : " + str(test_list))
  
# initializing K
K = 1
  
# initializing N 
N = 3
  
# Skipping N using 3rd param of range()
res = [test_list[idx][K] for idx in range(0, len(test_list), N)]
  
# printing result 
print("The extracted elements : " + str(res))

输出

The original list is : [(4, 5, 3), (3, 4, 7), (4, 3, 2), (4, 7, 8), (6, 4, 7), (2, 5, 7), (1, 9, 10), (3, 5, 7)]
The extracted elements : [5, 7, 9]