cfbd45bfc0
* Improve features * Add wasm32-wasi as a target * Update .github/workflows/ci.yml Co-authored-by: morenol <22335041+morenol@users.noreply.github.com>
105 lines
3.1 KiB
Rust
105 lines
3.1 KiB
Rust
//! # F-measure
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//!
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//! Harmonic mean of the precision and recall.
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//!
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//! \\[f1 = (1 + \beta^2)\frac{precision \times recall}{\beta^2 \times precision + recall}\\]
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//!
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//! where \\(\beta \\) is a positive real factor, where \\(\beta \\) is chosen such that recall is considered \\(\beta \\) times as important as precision.
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//!
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//! Example:
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//!
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//! ```
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//! use smartcore::metrics::f1::F1;
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//! use smartcore::metrics::Metrics;
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//! let y_pred: Vec<f64> = vec![0., 0., 1., 1., 1., 1.];
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//! let y_true: Vec<f64> = vec![0., 1., 1., 0., 1., 0.];
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//!
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//! let beta = 1.0; // beta default is equal 1.0 anyway
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//! let score: f64 = F1::new_with(beta).get_score(&y_pred, &y_true);
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//! ```
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//!
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//! <script src="https://polyfill.io/v3/polyfill.min.js?features=es6"></script>
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//! <script id="MathJax-script" async src="https://cdn.jsdelivr.net/npm/mathjax@3/es5/tex-mml-chtml.js"></script>
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use std::marker::PhantomData;
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#[cfg(feature = "serde")]
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use serde::{Deserialize, Serialize};
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use crate::linalg::basic::arrays::ArrayView1;
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use crate::metrics::precision::Precision;
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use crate::metrics::recall::Recall;
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use crate::numbers::basenum::Number;
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use crate::numbers::floatnum::FloatNumber;
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use crate::numbers::realnum::RealNumber;
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use crate::metrics::Metrics;
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/// F-measure
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#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
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#[derive(Debug)]
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pub struct F1<T> {
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/// a positive real factor
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pub beta: f64,
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_phantom: PhantomData<T>,
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}
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impl<T: Number + RealNumber + FloatNumber> Metrics<T> for F1<T> {
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fn new() -> Self {
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let beta: f64 = 1f64;
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Self {
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beta,
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_phantom: PhantomData,
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}
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}
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/// create a typed object to call Recall functions
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fn new_with(beta: f64) -> Self {
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Self {
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beta,
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_phantom: PhantomData,
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}
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}
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/// Computes F1 score
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/// * `y_true` - cround truth (correct) labels.
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/// * `y_pred` - predicted labels, as returned by a classifier.
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fn get_score(&self, y_true: &dyn ArrayView1<T>, y_pred: &dyn ArrayView1<T>) -> f64 {
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if y_true.shape() != y_pred.shape() {
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panic!(
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"The vector sizes don't match: {} != {}",
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y_true.shape(),
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y_pred.shape()
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);
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}
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let beta2 = self.beta * self.beta;
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let p = Precision::new().get_score(y_true, y_pred);
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let r = Recall::new().get_score(y_true, y_pred);
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(1f64 + beta2) * (p * r) / ((beta2 * p) + r)
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}
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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#[cfg_attr(
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all(target_arch = "wasm32", not(target_os = "wasi")),
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wasm_bindgen_test::wasm_bindgen_test
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)]
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#[test]
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fn f1() {
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let y_pred: Vec<f64> = vec![0., 0., 1., 1., 1., 1.];
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let y_true: Vec<f64> = vec![0., 1., 1., 0., 1., 0.];
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let beta = 1.0;
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let score1: f64 = F1::new_with(beta).get_score(&y_pred, &y_true);
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let score2: f64 = F1::new_with(beta).get_score(&y_true, &y_true);
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println!("{:?}", score1);
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println!("{:?}", score2);
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assert!((score1 - 0.57142857).abs() < 1e-8);
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assert!((score2 - 1.0).abs() < 1e-8);
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}
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}
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