Python - 将周围元素转换为 K

给定 Matrix，从每一行获取 K 的周围元素（如果存在）。

Input : test_list = [[7, 6, 3, 2], [5, 6], [2, 1], [6, 1, 2]], K = 6 
Output : [[7, 3], [5], [], [1]] 
Explanation : All elements surrounded by 6 are extracted.

Input : test_list = [[7, 6, 3, 2], [5, 6], [2, 1], [6, 1, 2]], K = 1 
Output : [[], [], [2], [6, 2]] 
Explanation : All elements surrounded by 1 are removed. 
 

方法#1：使用index() + loop + try/except

在这里，我们使用 index() 检查元素的索引，然后通过访问下一个和上一个元素来获取所需的周围元素。如果该元素不存在，则返回一个空列表。

Python3

# Python3 code to demonstrate working of 
# Surrounding elements to K
# Using index() + loop + try/except
  
# initializing list
test_list = [[7, 6, 3, 2], [5, 6], [2, 1], [6, 1, 2]]
  
# printing original list
print("The original list is : " + str(test_list))
  
# initializing K 
K = 6
  
res = []
for sub in test_list:
      
    # getting index 
    try :
        idx = sub.index(K)
    except Exception as e :
        res.append([])
        continue
      
    # appending Surrounding elements
    if idx != 0 and idx != len(sub) - 1:
        res.append([sub[idx - 1], sub[idx + 1]])
    elif idx == 0:
        res.append([sub[idx + 1]])
    else : res.append([sub[idx - 1]])
  
# printing result 
print("The Surrounding elements : " + str(res))

输出：

The original list is : [[7, 6, 3, 2], [5, 6], [2, 1], [6, 1, 2]]
The Surrounding elements : [[7, 3], [5], [], [1]]

方法#2：使用 index() + in 运算符 + loop

在这里，我们在应用 index() 之前检查元素是否存在于一行中，以避免使用 try/except 块。其余所有功能与上述方法相同。

蟒蛇3

# Python3 code to demonstrate working of
# Surrounding elements to K
# Using index() + in operator + loop
  
# initializing list
test_list = [[7, 6, 3, 2], [5, 6], [2, 1], [6, 1, 2]]
  
# printing original list
print("The original list is : " + str(test_list))
  
# initializing K
K = 6
  
res = []
for sub in test_list:
  
    # getting index
    # checking for element presence in row
    if K in sub:
        idx = sub.index(K)
    else:
        res.append([])
        continue
  
    # appending Surrounding elements
    if idx != 0 and idx != len(sub) - 1:
        res.append([sub[idx - 1], sub[idx + 1]])
    elif idx == 0:
        res.append([sub[idx + 1]])
    else:
        res.append([sub[idx - 1]])
  
# printing result
print("The Surrounding elements : " + str(res))

输出：

The original list is : [[7, 6, 3, 2], [5, 6], [2, 1], [6, 1, 2]]
The Surrounding elements : [[7, 3], [5], [], [1]]