如何在polars中将两列组合成“{key:value}”对?

你可以试试这个代码片段,这似乎是你能得到的最接近pl的格言。

参见参考文献: data_types_polaris

import polars as pl

df = pl.DataFrame(
    {"name": ["Chuck", "John", "Alice"], "surname": ["Dalliston", "Doe", "Smith"]}
)

df = df.select(
    [
        "name",
        "surname",
        (
            pl.struct(["name", "surname"]).map_elements(
                lambda row: {row["name"]: row["surname"]}, return_dtype=pl.Object
            )
        ).alias("name_surname"),
    ]
)
print(df)

┌───────┬───────────┬────────────────────────┐
│ name  ┆ surname   ┆ name_surname           │
│ ---   ┆ ---       ┆ ---                    │
│ str   ┆ str       ┆ object                 │
╞═══════╪═══════════╪════════════════════════╡
│ Chuck ┆ Dalliston ┆ {'Chuck': 'Dalliston'} │
│ John  ┆ Doe       ┆ {'John': 'Doe'}        │
│ Alice ┆ Smith     ┆ {'Alice': 'Smith'}     │
└───────┴───────────┴────────────────────────┘

import polars as pl

df = pl.DataFrame(
    {"name": ["Chuck", "John", "Alice"], "surname": ["Dalliston", "Doe", "Smith"]}
)
df = df.with_columns(
            json=pl.concat_str(
                pl.lit("{"),
                pl.col("specification_name"),
                pl.lit(":"),
                pl.col("specification_value"),
                pl.lit("}"),
                separator='"',
            )
        )

这将返回一个json字符串