python - 从 pandas 数据帧和相应的时间戳中提取阶段/段

Question

我有以下数据框

       Sleep Stage  Time[hh:mm:ss]  Event   Duration[s]
    0   SLEEP-S0    23:27:14    SLEEP-S0    30
    1   SLEEP-S0    23:27:44    SLEEP-S0    30
    2   SLEEP-MT    23:28:14    SLEEP-MT    30
    3   SLEEP-S0    23:28:44    SLEEP-S0    30
    4   SLEEP-S0    23:29:14    SLEEP-S0    30
    ... ... ... ... ...
   1022 SLEEP-REM   07:57:14    SLEEP-REM   30
   1023 SLEEP-REM   07:57:44    SLEEP-REM   30
   1024 SLEEP-S2    07:58:14    SLEEP-S2    30
   1025 SLEEP-S2    07:58:44    SLEEP-S2    30
   1026 SLEEP-S2    07:59:14    SLEEP-S2    30

我想创建包含阶段、该阶段的开始时间和该阶段的结束时间的段。请注意，这些阶段可能会重复。例如，我想要这样的东西:

 STAGE        START_POINT        END_POINT      DURATION
SLEEP-S0       23:27:14          23:28:14        60
SLEEP-MT       23:28:14          23:28:44        30    
SLEEP-S0        ...                ...           ...

有人可以帮我吗？

Answer 1

您的问题是岛屿与缺口问题的变体。每次Stage发生变化时，它都会创建一个新的岛屿。一座岛的结束就是下一座岛的开始。

# Every time the Stage changes from the previous row, it creates a new island
islands = df["Stage"].ne(df["Stage"].shift()).rename("island").cumsum()

# Convert the Time column to time for easier calculation
time = pd.to_datetime(df["Time"])

# If left alone "00:01:00" will convert to 12:01 AM *today* but it's most likely
# mean 12:01 AM *the next day*. We need some special handling for time in the
# wee hours.
time = time.mask(time < pd.Timestamp.now().replace(hour=12, minute=0, second=0), time + pd.Timedelta(hours=24))

# Each island has the same Stage across all rows
result = time.groupby([islands, df["Stage"]]).agg(START_POINT="min")

# END_POINT is START_POINT of the next stage
result["END_POINT"] = result["START_POINT"].shift(-1)

# DURATION is measured in seconds
result["DURATION"] = (result["END_POINT"] - result["START_POINT"]) / pd.Timedelta(seconds=1)

# Format the START_POINT and END_POINT back to strings
for col in ["START_POINT", "END_POINT"]:
    result[col] = result[col].dt.strftime("%H:%M:%S")