| <!DOCTYPE html><html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta name="generator" content="rustdoc"><meta name="description" content="Source of the Rust file `/root/.cargo/git/checkouts/incubator-teaclave-crates-c8106113f74feefc/ede1f68/rusty-machine/src/learning/toolkit/cost_fn.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>cost_fn.rs - source</title><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../../SourceSerif4-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../../FiraSans-Regular.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../../FiraSans-Medium.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../../SourceCodePro-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../../SourceSerif4-Bold.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../../SourceCodePro-Semibold.ttf.woff2"><link rel="stylesheet" href="../../../../normalize.css"><link rel="stylesheet" href="../../../../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" href="../../../../ayu.css" disabled><link rel="stylesheet" href="../../../../dark.css" disabled><link rel="stylesheet" href="../../../../light.css" id="themeStyle"><script id="default-settings" ></script><script src="../../../../storage.js"></script><script defer src="../../../../source-script.js"></script><script defer src="../../../../source-files.js"></script><script defer src="../../../../main.js"></script><noscript><link rel="stylesheet" href="../../../../noscript.css"></noscript><link rel="alternate icon" type="image/png" href="../../../../favicon-16x16.png"><link rel="alternate icon" type="image/png" href="../../../../favicon-32x32.png"><link rel="icon" type="image/svg+xml" href="../../../../favicon.svg"></head><body class="rustdoc source"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><a class="sidebar-logo" href="../../../../rusty_machine/index.html"><div class="logo-container"><img class="rust-logo" src="../../../../rust-logo.svg" alt="logo"></div></a></nav><main><div class="width-limiter"><nav class="sub"><a class="sub-logo-container" href="../../../../rusty_machine/index.html"><img class="rust-logo" src="../../../../rust-logo.svg" alt="logo"></a><form class="search-form"><div class="search-container"><span></span><input class="search-input" name="search" autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"><div id="help-button" title="help" tabindex="-1"><a href="../../../../help.html">?</a></div><div id="settings-menu" tabindex="-1"><a href="../../../../settings.html" title="settings"><img width="22" height="22" alt="Change settings" src="../../../../wheel.svg"></a></div></div></form></nav><section id="main-content" class="content"><div class="example-wrap"><pre class="src-line-numbers"><span id="1">1</span> |
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| </pre><pre class="rust"><code><span class="doccomment">//! Cost Functions. |
| //! |
| //! This module contains a number of structs implementing the `CostFunc` trait. |
| //! |
| //! These structs are used within Neural Networks and |
| //! Generalized Linear Regression (not yet implemented). |
| //! |
| //! You can also create your own custom cost functions for use in your models. |
| //! Just create a struct implementing the `CostFunc` trait. |
| |
| </span><span class="kw">use </span>linalg::{Matrix, BaseMatrix, BaseMatrixMut}; |
| <span class="kw">use </span>linalg::Vector; |
| |
| <span class="doccomment">/// Trait for cost functions in models. |
| </span><span class="kw">pub trait </span>CostFunc<T> { |
| <span class="doccomment">/// The cost function. |
| </span><span class="kw">fn </span>cost(outputs: <span class="kw-2">&</span>T, targets: <span class="kw-2">&</span>T) -> f64; |
| |
| <span class="doccomment">/// The gradient of the cost function. |
| </span><span class="kw">fn </span>grad_cost(outputs: <span class="kw-2">&</span>T, targets: <span class="kw-2">&</span>T) -> T; |
| } |
| |
| <span class="doccomment">/// The mean squared error cost function. |
| </span><span class="attribute">#[derive(Clone, Copy, Debug)] |
| </span><span class="kw">pub struct </span>MeanSqError; |
| |
| <span class="comment">// For generics we need a trait for "Hadamard product" here |
| // Which is "Elementwise multiplication". |
| </span><span class="kw">impl </span>CostFunc<Matrix<f64>> <span class="kw">for </span>MeanSqError { |
| <span class="kw">fn </span>cost(outputs: <span class="kw-2">&</span>Matrix<f64>, targets: <span class="kw-2">&</span>Matrix<f64>) -> f64 { |
| <span class="kw">let </span>diff = outputs - targets; |
| <span class="kw">let </span>sq_diff = <span class="kw-2">&</span>diff.elemul(<span class="kw-2">&</span>diff); |
| |
| <span class="kw">let </span>n = diff.rows(); |
| |
| sq_diff.sum() / (<span class="number">2f64 </span>* (n <span class="kw">as </span>f64)) |
| } |
| |
| <span class="kw">fn </span>grad_cost(outputs: <span class="kw-2">&</span>Matrix<f64>, targets: <span class="kw-2">&</span>Matrix<f64>) -> Matrix<f64> { |
| outputs - targets |
| } |
| } |
| |
| <span class="kw">impl </span>CostFunc<Vector<f64>> <span class="kw">for </span>MeanSqError { |
| <span class="kw">fn </span>cost(outputs: <span class="kw-2">&</span>Vector<f64>, targets: <span class="kw-2">&</span>Vector<f64>) -> f64 { |
| <span class="kw">let </span>diff = outputs - targets; |
| <span class="kw">let </span>sq_diff = <span class="kw-2">&</span>diff.elemul(<span class="kw-2">&</span>diff); |
| |
| <span class="kw">let </span>n = diff.size(); |
| |
| sq_diff.sum() / (<span class="number">2f64 </span>* (n <span class="kw">as </span>f64)) |
| } |
| |
| <span class="kw">fn </span>grad_cost(outputs: <span class="kw-2">&</span>Vector<f64>, targets: <span class="kw-2">&</span>Vector<f64>) -> Vector<f64> { |
| outputs - targets |
| } |
| } |
| |
| <span class="doccomment">/// The cross entropy error cost function. |
| </span><span class="attribute">#[derive(Clone, Copy, Debug)] |
| </span><span class="kw">pub struct </span>CrossEntropyError; |
| |
| <span class="kw">impl </span>CostFunc<Matrix<f64>> <span class="kw">for </span>CrossEntropyError { |
| <span class="kw">fn </span>cost(outputs: <span class="kw-2">&</span>Matrix<f64>, targets: <span class="kw-2">&</span>Matrix<f64>) -> f64 { |
| <span class="comment">// The cost for a single |
| </span><span class="kw">let </span>log_inv_output = (-outputs + <span class="number">1f64</span>).apply(<span class="kw-2">&</span>ln); |
| <span class="kw">let </span>log_output = outputs.clone().apply(<span class="kw-2">&</span>ln); |
| |
| <span class="kw">let </span>mat_cost = targets.elemul(<span class="kw-2">&</span>log_output) + (-targets + <span class="number">1f64</span>).elemul(<span class="kw-2">&</span>log_inv_output); |
| |
| <span class="kw">let </span>n = outputs.rows(); |
| |
| -(mat_cost.sum()) / (n <span class="kw">as </span>f64) |
| } |
| |
| <span class="kw">fn </span>grad_cost(outputs: <span class="kw-2">&</span>Matrix<f64>, targets: <span class="kw-2">&</span>Matrix<f64>) -> Matrix<f64> { |
| (outputs - targets).elediv(<span class="kw-2">&</span>(outputs.elemul(<span class="kw-2">&</span>(-outputs + <span class="number">1f64</span>)))) |
| } |
| } |
| |
| <span class="kw">impl </span>CostFunc<Vector<f64>> <span class="kw">for </span>CrossEntropyError { |
| <span class="kw">fn </span>cost(outputs: <span class="kw-2">&</span>Vector<f64>, targets: <span class="kw-2">&</span>Vector<f64>) -> f64 { |
| <span class="comment">// The cost for a single |
| </span><span class="kw">let </span>log_inv_output = (-outputs + <span class="number">1f64</span>).apply(<span class="kw-2">&</span>ln); |
| <span class="kw">let </span>log_output = outputs.clone().apply(<span class="kw-2">&</span>ln); |
| |
| <span class="kw">let </span>mat_cost = targets.elemul(<span class="kw-2">&</span>log_output) + (-targets + <span class="number">1f64</span>).elemul(<span class="kw-2">&</span>log_inv_output); |
| |
| <span class="kw">let </span>n = outputs.size(); |
| |
| -(mat_cost.sum()) / (n <span class="kw">as </span>f64) |
| } |
| |
| <span class="kw">fn </span>grad_cost(outputs: <span class="kw-2">&</span>Vector<f64>, targets: <span class="kw-2">&</span>Vector<f64>) -> Vector<f64> { |
| (outputs - targets).elediv(<span class="kw-2">&</span>(outputs.elemul(<span class="kw-2">&</span>(-outputs + <span class="number">1f64</span>)))) |
| } |
| } |
| |
| <span class="doccomment">/// Logarithm for applying within cost function. |
| </span><span class="kw">fn </span>ln(x: f64) -> f64 { |
| x.ln() |
| } |
| </code></pre></div> |
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