remove duplicates in polars rust

Question

hi i am trying to remove duplicates based on a column "time" in my dataframe.

i read the official document which defines the unique() method as follows:

pub fn unique(
    &self,
    subset: Option<&[String]>,
    keep: UniqueKeepStrategy,
    slice: Option<(i64, usize)>
) -> PolarsResult<DataFrame>

but somehow when i executed :

fn main() -> Result<(), Box<dyn Error>> {
    let col_name = String::from("time");
    let df = read_csv()?.unique(vec![col_name], UniqueKeep::First)?;
    println!("{:?}", df);
    Ok(())
}

i got this error:

error[E0433]: failed to resolve: use of undeclared type `UniqueKeep`
   --> src/main.rs:155:49
    |
155 |     let df = read_csv()?.unique(vec![col_name], UniqueKeep::First)?;
    |                                                 ^^^^^^^^^^ use of undeclared type `UniqueKeep`

could it be some kind of missing import? i only loaded the prelude:

use polars::prelude::*;

ahh, i see. now it returns `an argument of type Option<(i64, usize)> is missing`, do you know what should i pass to this `slice: Option<(i64, usize)>` parameter ? — Arthur Zhang, Jun 08 '23 at 01:24

Arthur Zhang · Accepted Answer · 2023-06-08T06:50:41.700

1

the enum should be UniqueKeepStrategy, and the slice could be simply 'None'

also: use unique_stable instead to avoid order being meseed up.

edited Jun 08 '23 at 06:50

answered Jun 08 '23 at 02:08

Arthur Zhang

107
8

Where possible, please don't post screenshots of code or error messages so SO stays searchable and accessible. The mention of the function name (`unique_stable`) would have been sufficient. Also weird: This function is on `LazyFrame`, earlier you were working with `DataFrame`. – Caesar Jun 08 '23 at 05:57

remove duplicates in polars rust

1 Answers1