如何從文件的特定行中提取特定部分？

Question

我有一個 .yml 文件，我需要從特定行中提取特定部分。

這是文件的一部分（文件有 1200 多行，但結構始終相似）：

training:
trainings:
  - workout: Rec 016
    performed_at: 2020-06-25 09:04:16.295000076 Z
    star: false
    time: '00:04:00'
  - workout: Hanging knee raises endurance 10
    performed_at: 2020-06-25 08:59:11.871999979 Z
    star: true
    time: '00:00:28'
    repetitions: 10
  - workout: Str 700
    performed_at: 2020-06-25 08:57:51.039999961 Z
    star: true
    time: '00:15:30'
  - workout: Supermans technical 30
    performed_at: 2020-06-25 08:38:45.894000053 Z
    star: true
    time: '00:01:02'
  - workout: Toe touch crunches technical 20
    performed_at: 2020-06-25 08:37:05.439000129 Z
    star: true
    time: '00:00:54'
  - workout: Pre 028
    performed_at: 2020-06-25 08:35:33.243999958 Z
    star: false
    time: '00:06:30'
  - workout: Rec 001
    performed_at: 2020-06-22 22:51:38.947000026 Z
    star: false
    time: '00:05:01'
  - workout: Burpees standard 10
    performed_at: 2020-06-22 22:46:00.807000160 Z
    star: true
    time: '00:00:38'

額外信息：使用以下代碼：

df = pd.read_csv(r'text_data.yml')

with pd.option_context("display.max_rows", None, "display.max_columns", None):
    print(df)

這是文件轉換成的內容：

                                                    ---
0                                             training:
1                                            trainings:
2                                    - workout: Rec 016
3         performed_at: 2020-06-25 09:04:16.295000076 Z
4                                           star: false
5                                      time: '00:04:00'
6           - workout: Hanging knee raises endurance 10
7         performed_at: 2020-06-25 08:59:11.871999979 Z
8                                            star: true
9                                      time: '00:00:28'
10                                      repetitions: 10
11                                   - workout: Str 700
12        performed_at: 2020-06-25 08:57:51.039999961 Z
13                                           star: true
14                                     time: '00:15:30'
15                    - workout: Supermans technical 30
16        performed_at: 2020-06-25 08:38:45.894000053 Z
17                                           star: true
18                                     time: '00:01:02'
19           - workout: Toe touch crunches technical 20
20        performed_at: 2020-06-25 08:37:05.439000129 Z
21                                           star: true
22                                     time: '00:00:54'
23                                   - workout: Pre 028
24        performed_at: 2020-06-25 08:35:33.243999958 Z
25                                          star: false
26                                     time: '00:06:30'
27                                   - workout: Rec 001
28        performed_at: 2020-06-22 22:51:38.947000026 Z
29                                          star: false
30                                     time: '00:05:01'

我想要做的是提取以“performed_at：”開頭的行中的日期（只有日期，沒有別的）並將它們放入列表/數據幀中。

我將如何通過 Pandas 以最有效的方式執行此操作？

Answer 1

有關解決方案，請閱讀問題下的評論。 感謝@dm2。