elinor 0.4.0

Evaluation Library in Information Retrieval
Documentation 
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use std::collections::BTreeMap;

use crate::metrics::precision::compute_precision;
use crate::PredScore;
use crate::Relevance;
use crate::TrueScore;

/// Computes the average precision at k.
pub fn compute_average_precision<K>(
    trues: &BTreeMap<K, TrueScore>,
    sorted_preds: &[Relevance<K, PredScore>],
    k: usize,
    rel_lvl: TrueScore,
) -> f64
where
    K: Eq + Ord,
{
    let k = if k == 0 { sorted_preds.len() } else { k };
    if k == 0 {
        return 0.0;
    }
    let n_rels = trues.values().filter(|&&rel| rel >= rel_lvl).count();
    if n_rels == 0 {
        return 0.0;
    }
    let mut sum = 0.0;
    for (i, pred) in sorted_preds.iter().enumerate().take(k) {
        if let Some(&rel) = trues.get(&pred.doc_id) {
            if rel >= rel_lvl {
                sum += compute_precision(trues, sorted_preds, i + 1, rel_lvl);
            }
        }
    }
    sum / n_rels as f64
}