Crate colback 

colback

Column backed lists of structs.

Synopsis

This crate provides procedural macros that generate code to extract data from dataframes so that their column data can be used as a view into a proxy struct. You want to keep contiguous columnar data, but you want to be able to write normal code with type-safety and minimal boilerplate that is also performant.

What it does

This will first create some proxy view and reference structs based on a struct that you use a derive macro on. The derive macro then generates some code that will handle extracting the chunked arrays backing the dataframe columns, as well as proxy/view types for each row. These proxy types are populated using data from the dataframe, so each instance of a proxy struct corresponds directly to a row.

Example

use colback::ColbackView;
use polars::df;

#[derive(ColbackView)]
struct MyRow {
    col_a: u32,
    col_b: bool,
}
let df = df!["col_a" => [0u32, 1u32], "col_b" => [true, false]].unwrap();
let row_view = MyRow::view(&df).unwrap();
let row_ref = row_view.get(0).unwrap();
assert_eq!(row_ref.col_a, 0);
assert_eq!(row_ref.col_b, true);

Enums

ColbackError

Errors that can arise when trying to extract a dataframe to a row view.

Traits

ColbackView

Trait for a struct that contains a reference to a row of a dataframe.

Type Aliases

Result

Convenience alias for results from this crate.

Derive Macros

ColbackView