Rust 将JSON密钥转换为Polars DataFrame

如果性能很重要，那么@BallpointBen的版本不是你能得到的最快的版本；这里有一个更高性能的版本:

pub fn convert(json: &str) -> Result<DataFrame, Box<dyn Error>> {
    use serde::Deserialize;

    #[derive(Debug, Deserialize)]
    #[serde(untagged)]
    enum Values {
        String(Vec<String>),
        Double(Vec<f64>),
    }

    #[derive(Debug, Deserialize)]
    #[serde(rename_all = "UPPERCASE")]
    enum DataType {
        String,
        Double,
    }

    #[derive(Debug, Deserialize)]
    #[serde(rename_all = "camelCase")]
    struct Column {
        data_item_name: String,
        result: Values,
        data_type: DataType,
    }

    #[derive(Debug, Deserialize)]
    struct Data {
        data: Vec<Column>,
    }

    let data = serde_json::from_str::<Data>(json)?;
    let df = data
        .data
        .into_iter()
        .map(|column| match column.data_type {
            DataType::String => {
                let Values::String(values) = column.result else {
                    return Err("column type mismatch");
                };
                Ok(Series::new(&column.data_item_name, values))
            }
            DataType::Double => {
                let Values::Double(values) = column.result else {
                    return Err("column type mismatch");
                };
                Ok(Series::from_vec(&column.data_item_name, values))
            }
        })
        .collect::<Result<DataFrame, _>>()?;

    Ok(df)
}

包含1,000个随机条目的基准:

BallpointBen            time:   [338.41 µs 340.05 µs 341.85 µs]
Found 2 outliers among 100 measurements (2.00%)
  2 (2.00%) high mild

Mine                    time:   [195.82 µs 196.79 µs 197.95 µs]
Found 11 outliers among 100 measurements (11.00%)
  8 (8.00%) high mild
  3 (3.00%) high severe