ChunkSet in polars::prelude - Rust (original) (raw)

pub trait ChunkSet<'a, A, B> {
    // Required methods
    fn scatter_single<I>(
        &'a self,
        idx: I,
        opt_value: Option<A>,
    ) -> Result<Self, PolarsError>
       where I: IntoIterator<Item = u32>,
             Self: Sized;
    fn scatter_with<I, F>(&'a self, idx: I, f: F) -> Result<Self, PolarsError>
       where I: IntoIterator<Item = u32>,
             Self: Sized,
             F: Fn(Option<A>) -> Option<B>;
    fn set(
        &'a self,
        mask: &ChunkedArray<BooleanType>,
        opt_value: Option<A>,
    ) -> Result<Self, PolarsError>
       where Self: Sized;
}

Expand description

Create a ChunkedArray with new values by index or by boolean mask.

Note that these operations clone data. This is however the only way we can modify at mask or index level as the underlying Arrow arrays are immutable.

Source

Set the values at indexes idx to some optional value Option<T>.

§Example

let ca = UInt32Chunked::new("a".into(), &[1, 2, 3]);
let new = ca.scatter_single(vec![0, 1], Some(10)).unwrap();

assert_eq!(Vec::from(&new), &[Some(10), Some(10), Some(3)]);

Source

Set the values at indexes idx by applying a closure to these values.

§Example

let ca = Int32Chunked::new("a".into(), &[1, 2, 3]);
let new = ca.scatter_with(vec![0, 1], |opt_v| opt_v.map(|v| v - 5)).unwrap();

assert_eq!(Vec::from(&new), &[Some(-4), Some(-3), Some(3)]);

Source

Set the values where the mask evaluates to true to some optional value Option<T>.

§Example

let ca = Int32Chunked::new("a".into(), &[1, 2, 3]);
let mask = BooleanChunked::new("mask".into(), &[false, true, false]);
let new = ca.set(&mask, Some(5)).unwrap();
assert_eq!(Vec::from(&new), &[Some(1), Some(5), Some(3)]);