我的DataFrame中有一个Utf8列，我想从该列创建一个List<Utf8>列。
具体来说，对于每一行，我都将获取HTML文档的文本，并使用soup解析出<p>类的所有段落，并将每个单独段落的文本集合存储为Vec<String>或Vec<&str>。

fn parse_paragraph(s: &str) -> Vec<&str> {

    let soup = Soup::new(s);
    
    soup.tag(p).find_all().iter().map(|&p| p.text()).collect()

}

在尝试修改Rust polars中应用自定义函数的几个可用示例时，我似乎无法编译转换。
以这个MVP为例，使用一个更简单的字符串到字符串向量的例子，借用了文档中的迭代器例子：

use polars::prelude::*;

fn vector_split(text: &str) -> Vec<&str> {

    text.split(' ').collect()
    
}

fn vector_split_series(s: &Series) -> PolarsResult<Series> {

    let output : Series = s.utf8()
        .expect("Text data")
        .into_iter()
        .map(|t| t.map(vector_split))
        .collect();

    Ok(output)
    
}

fn main() {

    let df = df! [
        "text" => ["a cat on the mat", "a bat on the hat", "a gnat on the rat"]
    ].unwrap();

    df.clone().lazy()
        .select([
            col("text").apply(|s| vector_split_series(&s), GetOutput::default())
                .alias("words")
        ])
        .collect();
    
}

(Note：我知道utf8系列有一个内置的split函数，但我需要一个比解析HTML更简单的示例）
我从cargo check得到以下错误：

error[E0277]: a value of type `polars::prelude::Series` cannot be built from an iterator over elements of type `Option<Vec<&str>>`
    --> src/main.rs:11:27
     |
11   |       let output : Series = s.utf8()
     |  ___________________________^
12   | |         .expect("Text data")
13   | |         .into_iter()
14   | |         .map(|t| t.map(vector_split))
     | |_____________________________________^ value of type `polars::prelude::Series` cannot be built from `std::iter::Iterator<Item=Option<Vec<&str>>>`
15   |           .collect();
     |            ------- required by a bound introduced by this call
     |
     = help: the trait `FromIterator<Option<Vec<&str>>>` is not implemented for `polars::prelude::Series`
     = help: the following other types implement trait `FromIterator<A>`:
               <polars::prelude::Series as FromIterator<&'a bool>>
               <polars::prelude::Series as FromIterator<&'a f32>>
               <polars::prelude::Series as FromIterator<&'a f64>>
               <polars::prelude::Series as FromIterator<&'a i32>>
               <polars::prelude::Series as FromIterator<&'a i64>>
               <polars::prelude::Series as FromIterator<&'a str>>
               <polars::prelude::Series as FromIterator<&'a u32>>
               <polars::prelude::Series as FromIterator<&'a u64>>
             and 15 others
note: required by a bound in `std::iter::Iterator::collect`

这种过程的正确用法是什么？有没有更简单的方法来应用函数？