Question

我在python中有此列表，下面是嵌套列表的列表，想要统计时间戳的出现次数并打印每个时间戳的计数。我该如何在python中做到这一点？

message= [['619833', 'Mon Jun  3 15:49:22 2019'], ['568391', 'Mon Jun  3 15:49:22 2019'], ['578934', 'Sat Jun  1 18:34:12 2019'], ['699425', 'Sat Jun  1 18:34:12 2019'], ['969231', 'Wed May 29 16:18:07 2019']]

预期结果：

['Mon Jun  3 15:49:22 2019', 2 ]
['Sat Jun  1 18:34:12 2019', 2 ]

这里是2。

Answer 1

这是@ArkistarvhKltzuonstev回复的编辑版本。

messages = [['619833', 'Mon Jun 3 15:49:22 2019'],['568391', 'Mon Jun 3 15:49:22 2019'],['578934', 'Sat Jun 1 18:34:12 2019'],['699425', 'Sat Jun 1 18:34:12 2019'],['969231', 'Wed May 29 16:18:07 2019']]

# Loop through each list
# Create a list called result which formats the data how you requested
result = [(k, sum(1 for i in messages if k in i)) for k in set(m[1] for m in messages)]
# Prints out that result list
print(result)

这是满足您需求的最快版本。

这是具有可重用功能的更完整的“程序”：

# Loop through each list
# Create a list called result which formats the data how you requested
def print_count(arr):
    result = [(k, sum(1 for i in arr if k in i)) for k in set(m[1] for m in arr)]
    print(result)

# Create a main function
def main():
    # Declare a list (like the one OP provided)
    messages = [['619833', 'Mon Jun 3 15:49:22 2019'],['568391', 'Mon Jun 3 15:49:22 2019'],['578934', 'Sat Jun 1 18:34:12 2019'],['699425', 'Sat Jun 1 18:34:12 2019'],['969231', 'Wed May 29 16:18:07 2019']]
    # Call the function
    print_count(messages)

# Call the main function
main()

Answer 2

您可以从Counter界面使用collections类。它会为您提供所有项目的计数，并且可以直接从列表中对其进行初始化。您可以使用列表推导从嵌套列表中选择所需的元素。

from collections import Counter

message = [['619833', 'Mon Jun  3 15:49:22 2019'],
['568391', 'Mon Jun  3 15:49:22 2019'],
['578934', 'Sat Jun  1 18:34:12 2019'],
['699425', 'Sat Jun  1 18:34:12 2019'],
['969231', 'Wed May 29 16:18:07 2019']]

print(Counter([x[1] for x in message]))

这将为您提供以下输出：

Counter({'Mon Jun  3 15:49:22 2019': 2, 'Sat Jun  1 18:34:12 2019': 2, 'Wed May 29 16:18:07 2019': 1})

您可以在柜台上使用most_common方法来获取您在问题中提到的结构：

>>> print(c.most_common())
[('Mon Jun  3 15:49:22 2019', 2), ('Sat Jun  1 18:34:12 2019', 2), ('Wed May 29 16:18:07 2019', 1)]

计算嵌套列表中重复项的出现次数

2 个答案: