无法解析polars_core，arrow::legacy，Dataframe是polars-lazy =“0.44.2”

Question

尽管：

1. 阅读polar_lazy 0.44.2

2. 安装成功

   cargo add polars-lazy

以下代码会导致错误：

• 错误[E0433]：无法解决：在

  legacy

  中找不到

  arrow

• 错误[E0433]：无法解决：使用未声明的板条箱或模块

  polars_core

• 错误[E0412]：在此范围内找不到类型

  PolarsResult

• 错误[E0412]：在此范围内找不到类型

  DataFrame

  use polars_core::prelude::*;
  use polars_core::df;
  use polars_lazy::prelude::*;
  use arrow::legacy::prelude::QuantileMethod;
  
  fn main() {
    let test = example()
    println!("show dataframe: {:?}", test);
  
  }
  
  fn example() -> PolarsResult<DataFrame> {
   let df = df!(
       "date" => ["2020-08-21", "2020-08-21", "2020-08-22", "2020-08-23", "2020-08-22"],
       "temp" => [20, 10, 7, 9, 1],
       "rain" => [0.2, 0.1, 0.3, 0.1, 0.01]
   )?;
  
   df.lazy()
   .group_by([col("date")])
   .agg([
       col("rain").min().alias("min_rain"),
       col("rain").sum().alias("sum_rain"),
       col("rain").quantile(lit(0.5), QuantileMethod::Nearest).alias("median_rain"),
   ])
   .sort(["date"], Default::default())
   .collect()
  }
  

注：

Cargo.toml

[dependencies]
arrow = "53.2.0"
polars-lazy = "0.44.2"

Answer 1

要使用

polars_core

，您必须将

polars-core

添加到您的依赖项中。

arrow

是

polars-arrow

的重命名导入：

[dependencies.arrow]
default-features = false
features = ["compute_aggregate", "compute_arithmetics", "compute_bitwise", "compute_boolean", "compute_boolean_kleene", "compute_cast", "compute_comparison"]
package = "polars-arrow"
version = "0.44.2"

因此您应该从依赖项中删除

arrow = "53.2.0"

并添加：

polars-core = "0.44.2"
arrow = { version = "0.44.2", package = "polars-arrow" }