Python – 最大 N 个重复元素

给定元素列表，如果一个元素在列表中的出现增加超过 N，则删除它。

Input  :  test_list = [6, 4, 6, 3, 6], N = 1

Output : [6, 4, 3]

Explanation :  The occurrence 2nd onwards of 6 are removed.

Input  :  test_list = [6, 4, 6, 3, 6], N = 2

Output : [6, 4, 6, 3]

Explanation :  The occurrence 3nd onwards of 6 are removed.

方法 #1：使用循环 + count()

上述功能的组合可以用来解决这个问题。在此，我们执行元素的迭代，并使用 count() 检查 count 是否大于该元素的 N，如果是，则删除该元素。

Python3

# Python3 code to demonstrate working of
# Maximum N repeated Elements
# Using loop + count()
  
# initializing list
test_list = [5, 7, 7, 2, 5, 5, 7, 2, 2]
  
# printing original list
print("The original list : " + str(test_list))
  
# initializing N
N = 2
  
# Using loop + count()
res = []
for ele in test_list:
  
    # checking of elements occurrence is not greater than N
    if res.count(ele) < N:
        res.append(ele)
  
# printing result
print("Extracted elements : " + str(res))

输出

The original list : [5, 7, 7, 2, 5, 5, 7, 2, 2]
Extracted elements : [5, 7, 7, 2, 5, 2]

方法 #2：使用 Counter() + 循环

这是可以执行此任务的另一种方式。在此，我们使用 Counter() 来执行元素计数，然后如果小于 N，则附加其大小的元素，如果大于，则使用列表推导将元素扩展到 N。不保留顺序。

Python3

# Python3 code to demonstrate working of
# Maximum N repeated Elements
# Using Counter() + loop
from collections import Counter
  
# initializing list
test_list = [5, 7, 7, 2, 5, 5, 7, 2, 2]
  
# printing original list
print("The original list : " + str(test_list))
  
# initializing N
N = 2
  
# Using Counter() + loop
res = []
temp = Counter(test_list)
for key, ele in temp.items():
  
    # Conditional check for size decision during append
    if ele <= N:
        res.extend([key for idx in range(ele)])
    else:
        res.extend([key for idx in range(N)])
  
# printing result
print("Extracted elements : " + str(res))

输出

The original list : [5, 7, 7, 2, 5, 5, 7, 2, 2]
Extracted elements : [5, 5, 7, 7, 2, 2]