如何使用 Python 返回文本文件中最新字段的行？

Question

我正在编写一个 Python 脚本。我需要从文本文件中返回包含最新 'timestamp': field 的行。例如，在下面的文本文件示例中：

{'uid': 3167, 'user_id': '6', 'timestamp': datetime.datetime(2021, 3, 10, 18, 7, 13), 'status': 1, 'punch': 1}, {'uid': 3168, 'user_id': '198', 'timestamp': datetime.datetime(2021, 3, 10, 18, 10, 42), 'status': 2, 'punch': 1}, {'uid': 3169, 'user_id': '3', 'timestamp': datetime.datetime(2021, 3, 10, 18, 13, 53), 'status': 1, 'punch': 1}, {'uid': 3170, 'user_id': '13', 'timestamp': datetime.datetime(2021, 3, 10, 18, 22, 2), 'status': 1, 'punch': 1}, {'uid': 3171, 'user_id': '9', 'timestamp': datetime.datetime(2021, 3, 10, 18, 22, 43), 'status': 1, 'punch': 1}, {'uid': 3172, 'user_id': '15', 'timestamp': datetime.datetime(2021, 3, 10, 18, 32, 30), 'status': 2, 'punch': 1}, {'uid': 3173, 'user_id': '4', 'timestamp': datetime.datetime(2021, 3, 10, 19, 42, 26), 'status': 1, 'punch': 1}, {'uid': 3174, 'user_id': '1', 'timestamp': datetime.datetime(2021, 3, 10, 19, 42, 34), 'status': 1, 'punch': 1}, {'uid': 3175, 'user_id': '3', 'timestamp': datetime.datetime(2021, 3, 11, 8, 48, 6), 'status': 1, 'punch': 1}, {'uid': 3176, 'user_id': '7', 'timestamp': datetime.datetime(2021, 3, 11, 9, 2, 30), 'status': 2, 'punch': 1}, {'uid': 3177, 'user_id': '5', 'timestamp': datetime.datetime(2021, 3, 11, 9, 12, 40), 'status': 1, 'punch': 1}, {'uid': 3178, 'user_id': '6', 'timestamp': datetime.datetime(2021, 3, 11, 9, 40, 47), 'status': 1, 'punch': 1}, {'uid': 3179, 'user_id': '15', 'timestamp': datetime.datetime(2021, 3, 11, 9, 49, 59), 'status': 2, 'punch': 1},

返回文本文件“今天的日期 2021 年 11 月 3 日”例如：

{'uid': 3175, 'user_id': '3', 'timestamp': datetime.datetime(2021, 3, 11, 8, 48, 6), 'status': 1, 'punch': 1}, {'uid': 3176, 'user_id': '7', 'timestamp': datetime.datetime(2021, 3, 11, 9, 2, 30), 'status': 2, 'punch': 1}, {'uid': 3177, 'user_id': '5', 'timestamp': datetime.datetime(2021, 3, 11, 9, 12, 40), 'status': 1, 'punch': 1}, {'uid': 3178, 'user_id': '6', 'timestamp': datetime.datetime(2021, 3, 11, 9, 40, 47), 'status': 1, 'punch': 1}, {'uid': 3179, 'user_id': '15', 'timestamp': datetime.datetime(2021, 3, 11, 9, 49, 59), 'status': 2, 'punch': 1},

Answer 1

您似乎正在处理表格数据，而 pandas 对此非常自然。

import datetime
import pandas as pd

df = pd.DataFrame([{'uid': 3167, 'user_id': '6', 'timestamp': datetime.datetime(2021, 3, 10, 18, 7, 13), 'status': 1, 'punch': 1}, {'uid': 3168, 'user_id': '198', 'timestamp': datetime.datetime(2021, 3, 10, 18, 10, 42), 'status': 2, 'punch': 1}, {'uid': 3169, 'user_id': '3', 'timestamp': datetime.datetime(2021, 3, 10, 18, 13, 53), 'status': 1, 'punch': 1}, {'uid': 3170, 'user_id': '13', 'timestamp': datetime.datetime(2021, 3, 10, 18, 22, 2), 'status': 1, 'punch': 1}, {'uid': 3171, 'user_id': '9', 'timestamp': datetime.datetime(2021, 3, 10, 18, 22, 43), 'status': 1, 'punch': 1}, {'uid': 3172, 'user_id': '15', 'timestamp': datetime.datetime(2021, 3, 10, 18, 32, 30), 'status': 2, 'punch': 1}, {'uid': 3173, 'user_id': '4', 'timestamp': datetime.datetime(2021, 3, 10, 19, 42, 26), 'status': 1, 'punch': 1}, {'uid': 3174, 'user_id': '1', 'timestamp': datetime.datetime(2021, 3, 10, 19, 42, 34), 'status': 1, 'punch': 1}, {'uid': 3175, 'user_id': '3', 'timestamp': datetime.datetime(2021, 3, 11, 8, 48, 6), 'status': 1, 'punch': 1}, {'uid': 3176, 'user_id': '7', 'timestamp': datetime.datetime(2021, 3, 11, 9, 2, 30), 'status': 2, 'punch': 1}, {'uid': 3177, 'user_id': '5', 'timestamp': datetime.datetime(2021, 3, 11, 9, 12, 40), 'status': 1, 'punch': 1}, {'uid': 3178, 'user_id': '6', 'timestamp': datetime.datetime(2021, 3, 11, 9, 40, 47), 'status': 1, 'punch': 1}, {'uid': 3179, 'user_id': '15', 'timestamp': datetime.datetime(2021, 3, 11, 9, 49, 59), 'status': 2, 'punch': 1},])

today = pd.to_datetime('today').normalize()
rows = df[df['timestamp'] >= today]

这给了

     uid user_id           timestamp  status  punch
8   3175       3 2021-03-11 08:48:06       1      1
9   3176       7 2021-03-11 09:02:30       2      1
10  3177       5 2021-03-11 09:12:40       1      1
11  3178       6 2021-03-11 09:40:47       1      1
12  3179      15 2021-03-11 09:49:59       2      1

如果您希望结果出现在 dicts 列表中，则可以使用 rows.to_dict('records')。

---

如果没有 pandas，这将是一种类似的方法来获取今天的日期时间并迭代您的数据以过滤它们。

lines = [{'uid': 3167, 'user_id': '6', 'timestamp': datetime.datetime(2021, 3, 10, 18, 7, 13), 'status': 1, 'punch': 1}, {'uid': 3168, 'user_id': '198', 'timestamp': datetime.datetime(2021, 3, 10, 18, 10, 42), 'status': 2, 'punch': 1}, {'uid': 3169, 'user_id': '3', 'timestamp': datetime.datetime(2021, 3, 10, 18, 13, 53), 'status': 1, 'punch': 1}, {'uid': 3170, 'user_id': '13', 'timestamp': datetime.datetime(2021, 3, 10, 18, 22, 2), 'status': 1, 'punch': 1}, {'uid': 3171, 'user_id': '9', 'timestamp': datetime.datetime(2021, 3, 10, 18, 22, 43), 'status': 1, 'punch': 1}, {'uid': 3172, 'user_id': '15', 'timestamp': datetime.datetime(2021, 3, 10, 18, 32, 30), 'status': 2, 'punch': 1}, {'uid': 3173, 'user_id': '4', 'timestamp': datetime.datetime(2021, 3, 10, 19, 42, 26), 'status': 1, 'punch': 1}, {'uid': 3174, 'user_id': '1', 'timestamp': datetime.datetime(2021, 3, 10, 19, 42, 34), 'status': 1, 'punch': 1}, {'uid': 3175, 'user_id': '3', 'timestamp': datetime.datetime(2021, 3, 11, 8, 48, 6), 'status': 1, 'punch': 1}, {'uid': 3176, 'user_id': '7', 'timestamp': datetime.datetime(2021, 3, 11, 9, 2, 30), 'status': 2, 'punch': 1}, {'uid': 3177, 'user_id': '5', 'timestamp': datetime.datetime(2021, 3, 11, 9, 12, 40), 'status': 1, 'punch': 1}, {'uid': 3178, 'user_id': '6', 'timestamp': datetime.datetime(2021, 3, 11, 9, 40, 47), 'status': 1, 'punch': 1}, {'uid': 3179, 'user_id': '15', 'timestamp': datetime.datetime(2021, 3, 11, 9, 49, 59), 'status': 2, 'punch': 1},]

today = datetime.date.today()
today = datetime.datetime(today.year, today.month, today.day)
result = [line for line in lines if line['timestamp'] >= today]