在波拉斯语组内排名?

创建列的结构 c2 , c3 使用 pl.struct("c2", "c3") ,计算稠密秩 c1 ,然后减去1,因为默认情况下排名从1开始:

pl.struct("c2", "c3").rank("dense").over("c1") - 1

完整代码:

import polars as pl

df = pl.DataFrame(
    {
        "c1": ["a", "a", "a", "a", "d", "d"],
        "c2": ["a", "a", "b", "c", "a", "b"],
        "c3": [1, 1, 1, 1, 1, 1],
    }
)

df2 = df.with_columns(rank=pl.struct("c2", "c3").rank("dense").over("c1") - 1)

print(df2)

输出

┌─────┬─────┬─────┬──────┐
│ c1  ┆ c2  ┆ c3  ┆ rank │
│ --- ┆ --- ┆ --- ┆ ---  │
│ str ┆ str ┆ i64 ┆ u32  │
╞═════╪═════╪═════╪══════╡
│ a   ┆ a   ┆ 1   ┆ 0    │
│ a   ┆ a   ┆ 1   ┆ 0    │
│ a   ┆ b   ┆ 1   ┆ 1    │
│ a   ┆ c   ┆ 1   ┆ 2    │
│ d   ┆ a   ┆ 1   ┆ 0    │
│ d   ┆ b   ┆ 1   ┆ 1    │
└─────┴─────┴─────┴──────┘