threshold-dict

A data structure to find smallest key that is larger than the query.

Suppose we have a following weight dependent price table.

weight,price
100,10
200,15
500,30
otherwise,50

The price is decided by the smallest entry whose weight key is greater than the query.

examples

• weight=90 -> price=10
• weight=100 -> price=15
• weight=250 -> price=30
• weight=600 -> price=50

Install

cargo add threshold_dict

Usage

A ThresholdDict can be created by passing kv pairs and a default func. If query is greater than or equal to all of the keys, the default func is used.

let kv_pairs = vec![(100, 10), (200, 15), (500, 30)];
let tree: BTreeMap<u32, u32> = kv_pairs.into_iter().collect();
let default_func = Box::new(|_: &u32| Some(50));
let dict = ThresholdDict::with_default_func(tree, default_func);

assert_eq!(dict.query(&90), Some(10));