问题

所以我有一个包含数字字符串的 Polars 列/系列。

```plaintext
s = pl.Series("a", ["111", "123", "101"])
s
shape: (3,)
Series: 'a' [str]
[
    "111"
    "123"
    "101"
]

我想要将每个字符串转换为整数列表。
我找到了一个可行的解决方案，但不确定是否最优。

s.str.split("").arr.shift(1).arr.slice(2).arr.eval(pl.element().str.parse_int(10))
shape: (3,)
Series: 'a' [list[i32]]
[
    [1, 1, 1]
    [1, 2, 3]
    [1, 0, 1]
]

我首先在每个点处拆分字符串。对于第一行，这会给我 [ "", "1", "1", "1", "" ]。从中，我想要移除第一个和最后一个条目（空字符串）。由于我事先不知道条目的长度，并且 slice 不允许指定结束索引，所以我选择了 shift -> slice 版本，但我觉得一定有更好的方法。

最后是 parse_int 的应用。

这似乎可以工作，但我想知道是否有更好的方法来执行这些步骤中的任何一个。

<details>
<summary>英文:</summary>

So i have a polars column/series that is strings of digits.

s = pl.Series("a", ["111","123","101"])
s
shape: (3,)
Series: 'a' [str]
[
"111"
"123"
"101"
]

I would like to convert each string into a list of integers.
I have found a working solution but i am not sure if it is optimal.

s.str.split("").arr.shift(1).arr.slice(2).arr.eval(pl.element().str.parse_int(10))
shape: (3,)
Series: 'a' [list[i32]]
[
[1, 1, 1]
[1, 2, 3]
[1, 0, 1]
]

I first split the strings at each point. For the first row this gives me `["","1","1","1",""]`. From this i want to remove the first and last entries (the empty string). Since i dont know the length of the entries beforehand and slice doesnt let one specify an end index i went with the shift -> slice version but i feel that there has to be a better way.

Lastly is the application of the parse_int.

This seems to be working but id like to know if there are better ways to do this or any of the individual steps.

</details>


# 答案1
**得分**: 5

[`.extract_all()`](https://pola-rs.github.io/polars/py-polars/html/reference/expressions/api/polars.Expr.str.extract_all.html) 和 [`.cast()`](https://pola-rs.github.io/polars/py-polars/html/reference/expressions/api/polars.Expr.cast.html#polars.Expr.cast)
```python
s.str.extract_all(r"\d").cast(pl.List(pl.Int64))

形状: (3,)
Series: 'a' [list[i64]]
[
	[1, 1, 1]
	[1, 2, 3]
	[1, 0, 1]
]

s.str.extract_all(r"\d").cast(pl.List(pl.Int64))

shape: (3,)
Series: 'a' [list[i64]]
[
	[1, 1, 1]
	[1, 2, 3]
	[1, 0, 1]
]