How to split a polars DataFrame into several dataframes in rust?

Question

I use Polars to read from a CSV file. I want to separate the DataFrame into several DataFrames by the "date" column (I want to analyze the data by day).

I tried to use partition_by but it seems not to be implemented (I got the error: "no method named partition_by found for mutable reference &mut DataFrame in the current scope method not found in &mut DataFrame").

Answer 1

rust-polars does implement partition_by, but you need to enable the partition_by feature in your Cargo.toml file.

[dependencies]
polars = { version = "0.39.2", features = ["lazy", "partition_by"] }

Example:

use polars::prelude::*;

fn main() {
    let df = df! (
        "a" => &["a", "b", "c", "a"],
        "b" => &[1, 2, 3, 2]
    )
    .unwrap();
    let dfs = df.partition_by(&["a"], true);
    println!("{:?}", dfs.unwrap());
}