Python 如何根据某些条件仅获取某些数据行

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这是我会怎么做的.这可能不是最干净的解决方案，但我认为它能做你想做的事情.

# Set up reproductible example (reprex)
import pandas as pd

df = pd.DataFrame({
    "Frame": ["liner", "platform", "liner", "liner", "platform",
              "liner", "platform", "liner", "platform", "liner"],
    "Type": ["group", "start", "single", "single", "end",
             "single", "start", "group", "end", "single"]
})

#    Frame       Type
# 0  liner       group
# 1  plateform   start
# 2  liner       single
# 3  liner       single
# 4  plateform   end
# 5  liner       single
# 6  plateform   start
# 7  liner       group
# 8  plateform   end
# 9  liner       single

步骤1:从平台的开始到结束 Select 行

start_indices = df.index[(df.Frame == "platform") & (df.Type == "start")]
end_indices = df.index[(df.Frame == "platform") & (df.Type == "end")]

df = pd.concat([
    df[start:end+1] for start, end in zip(start_indices, end_indices)
])

第二步:增加站台号栏目

df["Class"] = (
    pd.Series(
        [f"P{n}" for n in  range(1, len(start_indices) + 1)],
        index=start_indices
    )
    .reindex(df.index)
    .fillna(method="ffill")
)

这就是你能得到的:

df

#    Frame      Type    Class
# 1  platform   start   P1
# 2  liner      single  P1
# 3  liner      single  P1
# 4  platform   end     P1
# 6  platform   start   P2
# 7  liner      group   P2
# 8  platform   end     P2