Python |计算列表中某个元素的出现次数
原文:https://www . geesforgeks . org/python-count-occurs-element-list/
给定 Python 中的一个列表和一个数字 x，计算 x 在给定列表中出现的次数。 示例:
Input : lst = [15, 6, 7, 10, 12, 20, 10, 28, 10]
x = 10
Output : 3
10 appears three times in given list.
Input : lst = [8, 6, 8, 10, 8, 20, 10, 8, 8]
x = 16
Output : 0
方法 1(简单方法) 我们保留一个计数器，如果在列表中找到所需的元素，该计数器就会不断增加。
Python 3
# Python code to count the number of occurrences
def countX(lst, x):
count = 0
for ele in lst:
if (ele == x):
count = count + 1
return count
# Driver Code
lst = [8, 6, 8, 10, 8, 20, 10, 8, 8]
x = 8
print('{} has occurred {} times'.format(x, countX(lst, x)))
Output:
8 has occurred 5 times
方法二(使用 count()) 思路是使用列表方法 count() 来统计出现次数。
Python 3
# Python code to count the number of occurrences
def countX(lst, x):
return lst.count(x)
# Driver Code
lst = [8, 6, 8, 10, 8, 20, 10, 8, 8]
x = 8
print('{} has occurred {} times'.format(x, countX(lst, x)))
Output:
8 has occurred 5 times
方法 2(使用 Counter()) Counter 方法返回一个字典，所有元素作为键值对出现，其中 key 是元素，value 是该元素出现的次数。
Python 3
from collections import Counter
# declaring the list
l = [1, 1, 2, 2, 3, 3, 4, 4, 5, 5]
# driver program
x = 3
d = Counter(l)
print('{} has occurred {} times'.format(x, d[x]))
Output:
3 has occurred 2 times
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