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<!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="API documentation for the Rust `Distribution` trait in crate `rand`."><meta name="keywords" content="rust, rustlang, rust-lang, Distribution"><title>rand::distributions::Distribution - Rust</title><link rel="stylesheet" type="text/css" href="../../normalize.css"><link rel="stylesheet" type="text/css" href="../../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" type="text/css" href="../../dark.css"><link rel="stylesheet" type="text/css" href="../../light.css" id="themeStyle"><script src="../../storage.js"></script><noscript><link rel="stylesheet" href="../../noscript.css"></noscript><link rel="shortcut icon" href="https://www.rust-lang.org/favicon.ico"><style type="text/css">#crate-search{background-image:url("../../down-arrow.svg");}</style></head><body class="rustdoc trait"><!--[if lte IE 8]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><div class="sidebar-menu">&#9776;</div><a href='../../rand/index.html'><div class='logo-container'><img src='https://www.rust-lang.org/logos/rust-logo-128x128-blk.png' alt='logo'></div></a><p class='location'>Trait Distribution</p><div class="sidebar-elems"><div class="block items"><a class="sidebar-title" href="#required-methods">Required Methods</a><div class="sidebar-links"><a href="#tymethod.sample">sample</a></div><a class="sidebar-title" href="#provided-methods">Provided Methods</a><div class="sidebar-links"><a href="#method.sample_iter">sample_iter</a></div><a class="sidebar-title" href="#foreign-impls">Implementations on Foreign Types</a><div class="sidebar-links"><a href="#impl-Distribution%3CT%3E-for-%26%27a%20D">&amp;&#39;a D</a></div><a class="sidebar-title" href="#implementors">Implementors</a></div><p class='location'><a href='../index.html'>rand</a>::<wbr><a href='index.html'>distributions</a></p><script>window.sidebarCurrent = {name: 'Distribution', ty: 'trait', relpath: ''};</script><script defer src="sidebar-items.js"></script></div></nav><div class="theme-picker"><button id="theme-picker" aria-label="Pick another theme!"><img src="../../brush.svg" width="18" alt="Pick another theme!"></button><div id="theme-choices"></div></div><script src="../../theme.js"></script><nav class="sub"><form class="search-form js-only"><div class="search-container"><div><select id="crate-search"><option value="All crates">All crates</option></select><input class="search-input" name="search" autocomplete="off" spellcheck="false" placeholder="Click or press S to search, ? for more options…" type="search"></div><a id="settings-menu" href="../../settings.html"><img src="../../wheel.svg" width="18" alt="Change settings"></a></div></form></nav><section id="main" class="content"><h1 class='fqn'><span class='out-of-band'><span id='render-detail'><a id="toggle-all-docs" href="javascript:void(0)" title="collapse all docs">[<span class='inner'>&#x2212;</span>]</a></span><a class='srclink' href='../../src/rand/distributions/mod.rs.html#233-270' title='goto source code'>[src]</a></span><span class='in-band'>Trait <a href='../index.html'>rand</a>::<wbr><a href='index.html'>distributions</a>::<wbr><a class="trait" href=''>Distribution</a></span></h1><div class="docblock type-decl hidden-by-usual-hider"><pre class='rust trait'>pub trait Distribution&lt;T&gt; {
fn <a href='#tymethod.sample' class='fnname'>sample</a>&lt;R:&nbsp;<a class="trait" href="../../rand/trait.Rng.html" title="trait rand::Rng">Rng</a> + ?<a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Sized.html" title="trait core::marker::Sized">Sized</a>&gt;(&amp;self, rng: <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.reference.html">&amp;mut </a>R) -&gt; T;
fn <a href='#method.sample_iter' class='fnname'>sample_iter</a>&lt;'a, R&gt;(&amp;'a self, rng: <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.reference.html">&amp;'a mut </a>R) -&gt; <a class="struct" href="../../rand/distributions/struct.DistIter.html" title="struct rand::distributions::DistIter">DistIter</a>&lt;'a, Self, R, T&gt;<br>&nbsp;&nbsp;&nbsp; <span class="where">where<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Self: <a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Sized.html" title="trait core::marker::Sized">Sized</a>,<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;R: <a class="trait" href="../../rand/trait.Rng.html" title="trait rand::Rng">Rng</a></span>,
{ ... }
}</pre></div><div class='docblock'><p>Types (distributions) that can be used to create a random instance of <code>T</code>.</p>
<p>It is possible to sample from a distribution through both the
<code>Distribution</code> and [<code>Rng</code>] traits, via <code>distr.sample(&amp;mut rng)</code> and
<code>rng.sample(distr)</code>. They also both offer the <a href="Distribution::method.sample_iter"><code>sample_iter</code></a> method, which
produces an iterator that samples from the distribution.</p>
<p>All implementations are expected to be immutable; this has the significant
advantage of not needing to consider thread safety, and for most
distributions efficient state-less sampling algorithms are available.</p>
</div>
<h2 id='required-methods' class='small-section-header'>Required methods<a href='#required-methods' class='anchor'></a></h2><div class='methods'><h3 id='tymethod.sample' class='method'><code id='sample.v'>fn <a href='#tymethod.sample' class='fnname'>sample</a>&lt;R:&nbsp;<a class="trait" href="../../rand/trait.Rng.html" title="trait rand::Rng">Rng</a> + ?<a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Sized.html" title="trait core::marker::Sized">Sized</a>&gt;(&amp;self, rng: <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.reference.html">&amp;mut </a>R) -&gt; T</code></h3><div class='docblock'><p>Generate a random value of <code>T</code>, using <code>rng</code> as the source of randomness.</p>
</div></div><span class='loading-content'>Loading content...</span>
<h2 id='provided-methods' class='small-section-header'>Provided methods<a href='#provided-methods' class='anchor'></a></h2><div class='methods'><h3 id='method.sample_iter' class='method'><div class="important-traits"><div class='tooltip'><span class='tooltiptext'>Important traits for <a class="struct" href="../../rand/distributions/struct.DistIter.html" title="struct rand::distributions::DistIter">DistIter</a>&lt;'a, D, R, T&gt;</span></div><div class="content hidden"><h3 class="important">Important traits for <a class="struct" href="../../rand/distributions/struct.DistIter.html" title="struct rand::distributions::DistIter">DistIter</a>&lt;'a, D, R, T&gt;</h3><code class="content"><span class="where fmt-newline">impl&lt;'a, D, R, T&gt; <a class="trait" href="https://doc.rust-lang.org/nightly/core/iter/traits/iterator/trait.Iterator.html" title="trait core::iter::traits::iterator::Iterator">Iterator</a> for <a class="struct" href="../../rand/distributions/struct.DistIter.html" title="struct rand::distributions::DistIter">DistIter</a>&lt;'a, D, R, T&gt; <span class="where fmt-newline">where<br>&nbsp;&nbsp;&nbsp;&nbsp;D: <a class="trait" href="../../rand/distributions/trait.Distribution.html" title="trait rand::distributions::Distribution">Distribution</a>&lt;T&gt;,<br>&nbsp;&nbsp;&nbsp;&nbsp;R: <a class="trait" href="../../rand/trait.Rng.html" title="trait rand::Rng">Rng</a> + 'a,&nbsp;</span></span><span class="where fmt-newline"> type <a href='https://doc.rust-lang.org/nightly/core/iter/traits/iterator/trait.Iterator.html#associatedtype.Item' class="type">Item</a> = T;</span></code></div></div><code id='sample_iter.v'>fn <a href='#method.sample_iter' class='fnname'>sample_iter</a>&lt;'a, R&gt;(&amp;'a self, rng: <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.reference.html">&amp;'a mut </a>R) -&gt; <a class="struct" href="../../rand/distributions/struct.DistIter.html" title="struct rand::distributions::DistIter">DistIter</a>&lt;'a, Self, R, T&gt; <span class="where fmt-newline">where<br>&nbsp;&nbsp;&nbsp;&nbsp;Self: <a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Sized.html" title="trait core::marker::Sized">Sized</a>,<br>&nbsp;&nbsp;&nbsp;&nbsp;R: <a class="trait" href="../../rand/trait.Rng.html" title="trait rand::Rng">Rng</a>,&nbsp;</span></code></h3><div class='docblock'><p>Create an iterator that generates random values of <code>T</code>, using <code>rng</code> as
the source of randomness.</p>
<h1 id="example" class="section-header"><a href="#example">Example</a></h1>
<div class="example-wrap"><pre class="rust rust-example-rendered">
<span class="kw">use</span> <span class="ident">rand</span>::<span class="ident">thread_rng</span>;
<span class="kw">use</span> <span class="ident">rand</span>::<span class="ident">distributions</span>::{<span class="ident">Distribution</span>, <span class="ident">Alphanumeric</span>, <span class="ident">Uniform</span>, <span class="ident">Standard</span>};
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">rng</span> <span class="op">=</span> <span class="ident">thread_rng</span>();
<span class="comment">// Vec of 16 x f32:</span>
<span class="kw">let</span> <span class="ident">v</span>: <span class="ident">Vec</span><span class="op">&lt;</span><span class="ident">f32</span><span class="op">&gt;</span> <span class="op">=</span> <span class="ident">Standard</span>.<span class="ident">sample_iter</span>(<span class="kw-2">&amp;</span><span class="kw-2">mut</span> <span class="ident">rng</span>).<span class="ident">take</span>(<span class="number">16</span>).<span class="ident">collect</span>();
<span class="comment">// String:</span>
<span class="kw">let</span> <span class="ident">s</span>: <span class="ident">String</span> <span class="op">=</span> <span class="ident">Alphanumeric</span>.<span class="ident">sample_iter</span>(<span class="kw-2">&amp;</span><span class="kw-2">mut</span> <span class="ident">rng</span>).<span class="ident">take</span>(<span class="number">7</span>).<span class="ident">collect</span>();
<span class="comment">// Dice-rolling:</span>
<span class="kw">let</span> <span class="ident">die_range</span> <span class="op">=</span> <span class="ident">Uniform</span>::<span class="ident">new_inclusive</span>(<span class="number">1</span>, <span class="number">6</span>);
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">roll_die</span> <span class="op">=</span> <span class="ident">die_range</span>.<span class="ident">sample_iter</span>(<span class="kw-2">&amp;</span><span class="kw-2">mut</span> <span class="ident">rng</span>);
<span class="kw">while</span> <span class="ident">roll_die</span>.<span class="ident">next</span>().<span class="ident">unwrap</span>() <span class="op">!</span><span class="op">=</span> <span class="number">6</span> {
<span class="macro">println</span><span class="macro">!</span>(<span class="string">&quot;Not a 6; rolling again!&quot;</span>);
}</pre></div>
</div></div><span class='loading-content'>Loading content...</span>
<h2 id='foreign-impls' class='small-section-header'>Implementations on Foreign Types<a href='#foreign-impls' class='anchor'></a></h2><h3 id='impl-Distribution%3CT%3E-for-%26%27a%20D' class='impl'><code class='in-band'>impl&lt;'a, T, D:&nbsp;<a class="trait" href="../../rand/distributions/trait.Distribution.html" title="trait rand::distributions::Distribution">Distribution</a>&lt;T&gt;&gt; <a class="trait" href="../../rand/distributions/trait.Distribution.html" title="trait rand::distributions::Distribution">Distribution</a>&lt;T&gt; for <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.reference.html">&amp;'a </a>D</code><a href='#impl-Distribution%3CT%3E-for-%26%27a%20D' class='anchor'></a><a class='srclink' href='../../src/rand/distributions/mod.rs.html#272-276' title='goto source code'>[src]</a></h3><div class='impl-items'><h4 id='method.sample' class="method hidden"><code id='sample.v-1'>fn <a href='#method.sample' class='fnname'>sample</a>&lt;R:&nbsp;<a class="trait" href="../../rand/trait.Rng.html" title="trait rand::Rng">Rng</a> + ?<a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Sized.html" title="trait core::marker::Sized">Sized</a>&gt;(&amp;self, rng: <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.reference.html">&amp;mut </a>R) -&gt; T</code><a class='srclink' href='../../src/rand/distributions/mod.rs.html#273-275' title='goto source code'>[src]</a></h4></div><span class='loading-content'>Loading content...</span>
<h2 id='implementors' class='small-section-header'>Implementors<a href='#implementors' class='anchor'></a></h2><div class='item-list' id='implementors-list'><h3 id='impl-Distribution%3C%5Bf64%3B%202%5D%3E' class='impl'><code class='in-band'>impl Distribution&lt;<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.array.html">[</a><a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.f64.html">f64</a><a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.array.html">; 2]</a>&gt; for <a class="struct" href="../../rand/distributions/struct.UnitCircle.html" title="struct rand::distributions::UnitCircle">UnitCircle</a></code><a href='#impl-Distribution%3C%5Bf64%3B%202%5D%3E' class='anchor'></a><a class='srclink' href='../../src/rand/distributions/unit_circle.rs.html#42-60' title='goto source code'>[src]</a></h3><div class='impl-items'><h4 id='method.sample-1' class="method hidden"><code id='sample.v-2'>fn <a href='#method.sample-1' class='fnname'>sample</a>&lt;R:&nbsp;<a class="trait" href="../../rand/trait.Rng.html" title="trait rand::Rng">Rng</a> + ?<a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Sized.html" title="trait core::marker::Sized">Sized</a>&gt;(&amp;self, rng: <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.reference.html">&amp;mut </a>R) -&gt; <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.array.html">[</a><a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.f64.html">f64</a><a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.array.html">; 2]</a></code><a class='srclink' href='../../src/rand/distributions/unit_circle.rs.html#44-59' title='goto source code'>[src]</a></h4></div><h3 id='impl-Distribution%3C%5Bf64%3B%203%5D%3E' class='impl'><code class='in-band'>impl Distribution&lt;<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.array.html">[</a><a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.f64.html">f64</a><a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.array.html">; 3]</a>&gt; for <a class="struct" href="../../rand/distributions/struct.UnitSphereSurface.html" title="struct rand::distributions::UnitSphereSurface">UnitSphereSurface</a></code><a href='#impl-Distribution%3C%5Bf64%3B%203%5D%3E' class='anchor'></a><a class='srclink' href='../../src/rand/distributions/unit_sphere.rs.html#41-55' title='goto source code'>[src]</a></h3><div class='impl-items'><h4 id='method.sample-2' class="method hidden"><code id='sample.v-3'>fn <a href='#method.sample-2' class='fnname'>sample</a>&lt;R:&nbsp;<a class="trait" href="../../rand/trait.Rng.html" title="trait rand::Rng">Rng</a> + ?<a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Sized.html" title="trait core::marker::Sized">Sized</a>&gt;(&amp;self, rng: <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.reference.html">&amp;mut </a>R) -&gt; <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.array.html">[</a><a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.f64.html">f64</a><a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.array.html">; 3]</a></code><a class='srclink' href='../../src/rand/distributions/unit_sphere.rs.html#43-54' title='goto source code'>[src]</a></h4></div><h3 id='impl-Distribution%3Cbool%3E' class='impl'><code class='in-band'>impl Distribution&lt;<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.bool.html">bool</a>&gt; for <a class="struct" href="../../rand/distributions/struct.Bernoulli.html" title="struct rand::distributions::Bernoulli">Bernoulli</a></code><a href='#impl-Distribution%3Cbool%3E' class='anchor'></a><a class='srclink' href='../../src/rand/distributions/bernoulli.rs.html#110-118' title='goto source code'>[src]</a></h3><div class='impl-items'><h4 id='method.sample-3' class="method hidden"><code id='sample.v-4'>fn <a href
src="../../implementors/rand/distributions/trait.Distribution.js">
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