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    <title>rand::distributions::WeightedChoice - Rust</title>

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        <a href='../../rand/index.html'><img src='https://www.rust-lang.org/logos/rust-logo-128x128-blk.png' alt='logo' width='100'></a>
        <p class='location'>Struct WeightedChoice</p><div class="sidebar-elems"><div class="block items"><a class="sidebar-title" href="#methods">Methods</a><div class="sidebar-links"><a href="#method.new">new</a></div><a class="sidebar-title" href="#implementations">Trait Implementations</a><div class="sidebar-links"><a href="#impl-Debug">Debug</a><a href="#impl-Sample%3CT%3E">Sample&lt;T&gt;</a><a href="#impl-IndependentSample%3CT%3E">IndependentSample&lt;T&gt;</a></div></div><p class='location'><a href='../index.html'>rand</a>::<wbr><a href='index.html'>distributions</a></p><script>window.sidebarCurrent = {name: 'WeightedChoice', ty: 'struct', relpath: ''};</script><script defer src="sidebar-items.js"></script></div>
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<h1 class='fqn'><span class='in-band'>Struct <a href='../index.html'>rand</a>::<wbr><a href='index.html'>distributions</a>::<wbr><a class="struct" href=''>WeightedChoice</a></span><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>]
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               </span><a class='srclink' href='../../src/rand/distributions/mod.rs.html#126-129' title='goto source code'>[src]</a></span></h1>
<pre class='rust struct'>pub struct WeightedChoice&lt;'a, T:&nbsp;'a&gt; { /* fields omitted */ }</pre><div class='docblock'><p>A distribution that selects from a finite collection of weighted items.</p>
<p>Each item has an associated weight that influences how likely it
is to be chosen: higher weight is more likely.</p>
<p>The <code>Clone</code> restriction is a limitation of the <code>Sample</code> and
<code>IndependentSample</code> traits. Note that <code>&amp;T</code> is (cheaply) <code>Clone</code> for
all <code>T</code>, as is <code>u32</code>, so one can store references or indices into
another vector.</p>
<h1 id="example" class="section-header"><a href="#example">Example</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">use</span> <span class="ident">rand</span>::<span class="ident">distributions</span>::{<span class="ident">Weighted</span>, <span class="ident">WeightedChoice</span>, <span class="ident">IndependentSample</span>};

<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">items</span> <span class="op">=</span> <span class="macro">vec</span><span class="macro">!</span>(<span class="ident">Weighted</span> { <span class="ident">weight</span>: <span class="number">2</span>, <span class="ident">item</span>: <span class="string">&#39;a&#39;</span> },
                     <span class="ident">Weighted</span> { <span class="ident">weight</span>: <span class="number">4</span>, <span class="ident">item</span>: <span class="string">&#39;b&#39;</span> },
                     <span class="ident">Weighted</span> { <span class="ident">weight</span>: <span class="number">1</span>, <span class="ident">item</span>: <span class="string">&#39;c&#39;</span> });
<span class="kw">let</span> <span class="ident">wc</span> <span class="op">=</span> <span class="ident">WeightedChoice</span>::<span class="ident">new</span>(<span class="kw-2">&amp;</span><span class="kw-2">mut</span> <span class="ident">items</span>);
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">rng</span> <span class="op">=</span> <span class="ident">rand</span>::<span class="ident">thread_rng</span>();
<span class="kw">for</span> _ <span class="kw">in</span> <span class="number">0</span>..<span class="number">16</span> {
     <span class="comment">// on average prints &#39;a&#39; 4 times, &#39;b&#39; 8 and &#39;c&#39; twice.</span>
     <span class="macro">println</span><span class="macro">!</span>(<span class="string">&quot;{}&quot;</span>, <span class="ident">wc</span>.<span class="ident">ind_sample</span>(<span class="kw-2">&amp;</span><span class="kw-2">mut</span> <span class="ident">rng</span>));
}</pre>
</div>
                    <h2 id='methods' class='small-section-header'>
                      Methods<a href='#methods' class='anchor'></a>
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                <h3 id='impl' class='impl'><span class='in-band'><code>impl&lt;'a, T:&nbsp;<a class="trait" href="https://doc.rust-lang.org/nightly/core/clone/trait.Clone.html" title="trait core::clone::Clone">Clone</a>&gt; <a class="struct" href="../../rand/distributions/struct.WeightedChoice.html" title="struct rand::distributions::WeightedChoice">WeightedChoice</a>&lt;'a, T&gt;</code><a href='#impl' class='anchor'></a></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/rand/distributions/mod.rs.html#131-166' title='goto source code'>[src]</a></span></h3>
<div class='impl-items'><h4 id='method.new' class="method"><span id='new.v' class='invisible'><code>pub fn <a href='#method.new' class='fnname'>new</a>(items: <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.slice.html">&amp;'a mut [</a><a class="struct" href="../../rand/distributions/struct.Weighted.html" title="struct rand::distributions::Weighted">Weighted</a>&lt;T&gt;<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.slice.html">]</a>) -&gt; <a class="struct" href="../../rand/distributions/struct.WeightedChoice.html" title="struct rand::distributions::WeightedChoice">WeightedChoice</a>&lt;'a, T&gt;</code></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/rand/distributions/mod.rs.html#139-165' title='goto source code'>[src]</a></span></h4>
<div class='docblock'><p>Create a new <code>WeightedChoice</code>.</p>
<p>Panics if:</p>
<ul>
<li><code>items</code> is empty</li>
<li>the total weight is 0</li>
<li>the total weight is larger than a <code>u32</code> can contain.</li>
</ul>
</div></div>
            <h2 id='implementations' class='small-section-header'>
              Trait Implementations<a href='#implementations' class='anchor'></a>
            </h2>
        <h3 id='impl-Debug' class='impl'><span class='in-band'><code>impl&lt;'a, T:&nbsp;<a class="trait" href="https://doc.rust-lang.org/nightly/core/fmt/trait.Debug.html" title="trait core::fmt::Debug">Debug</a> + 'a&gt; <a class="trait" href="https://doc.rust-lang.org/nightly/core/fmt/trait.Debug.html" title="trait core::fmt::Debug">Debug</a> for <a class="struct" href="../../rand/distributions/struct.WeightedChoice.html" title="struct rand::distributions::WeightedChoice">WeightedChoice</a>&lt;'a, T&gt;</code><a href='#impl-Debug' class='anchor'></a></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/rand/distributions/mod.rs.html#125' title='goto source code'>[src]</a></span></h3>
<div class='impl-items'><h4 id='method.fmt' class="method"><span id='fmt.v' class='invisible'><code>fn <a href='https://doc.rust-lang.org/nightly/core/fmt/trait.Debug.html#tymethod.fmt' class='fnname'>fmt</a>(&amp;self, __arg_0: &amp;mut <a class="struct" href="https://doc.rust-lang.org/nightly/core/fmt/struct.Formatter.html" title="struct core::fmt::Formatter">Formatter</a>) -&gt; <a class="type" href="https://doc.rust-lang.org/nightly/core/fmt/type.Result.html" title="type core::fmt::Result">Result</a></code></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/rand/distributions/mod.rs.html#125' title='goto source code'>[src]</a></span></h4>
<div class='docblock'><p>Formats the value using the given formatter. <a href="https://doc.rust-lang.org/nightly/core/fmt/trait.Debug.html#tymethod.fmt">Read more</a></p>
</div></div><h3 id='impl-Sample%3CT%3E' class='impl'><span class='in-band'><code>impl&lt;'a, T:&nbsp;<a class="trait" href="https://doc.rust-lang.org/nightly/core/clone/trait.Clone.html" title="trait core::clone::Clone">Clone</a>&gt; <a class="trait" href="../../rand/distributions/trait.Sample.html" title="trait rand::distributions::Sample">Sample</a>&lt;T&gt; for <a class="struct" href="../../rand/distributions/struct.WeightedChoice.html" title="struct rand::distributions::WeightedChoice">WeightedChoice</a>&lt;'a, T&gt;</code><a href='#impl-Sample%3CT%3E' class='anchor'></a></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/rand/distributions/mod.rs.html#168-170' title='goto source code'>[src]</a></span></h3>
<div class='impl-items'><h4 id='method.sample' class="method"><span id='sample.v' class='invisible'><code>fn <a href='../../rand/distributions/trait.Sample.html#tymethod.sample' class='fnname'>sample</a>&lt;R:&nbsp;<a class="trait" href="../../rand/trait.Rng.html" title="trait rand::Rng">Rng</a>&gt;(&amp;mut self, rng: <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.reference.html">&amp;mut </a>R) -&gt; T</code></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/rand/distributions/mod.rs.html#169' title='goto source code'>[src]</a></span></h4>
<div class='docblock'><p>Generate a random value of <code>Support</code>, using <code>rng</code> as the source of randomness. <a href="../../rand/distributions/trait.Sample.html#tymethod.sample">Read more</a></p>
</div></div><h3 id='impl-IndependentSample%3CT%3E' class='impl'><span class='in-band'><code>impl&lt;'a, T:&nbsp;<a class="trait" href="https://doc.rust-lang.org/nightly/core/clone/trait.Clone.html" title="trait core::clone::Clone">Clone</a>&gt; <a class="trait" href="../../rand/distributions/trait.IndependentSample.html" title="trait rand::distributions::IndependentSample">IndependentSample</a>&lt;T&gt; for <a class="struct" href="../../rand/distributions/struct.WeightedChoice.html" title="struct rand::distributions::WeightedChoice">WeightedChoice</a>&lt;'a, T&gt;</code><a href='#impl-IndependentSample%3CT%3E' class='anchor'></a></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/rand/distributions/mod.rs.html#172-213' title='goto source code'>[src]</a></span></h3>
<div class='impl-items'><h4 id='method.ind_sample' class="method"><span id='ind_sample.v' class='invisible'><code>fn <a href='../../rand/distributions/trait.IndependentSample.html#tymethod.ind_sample' class='fnname'>ind_sample</a>&lt;R:&nbsp;<a class="trait" href="../../rand/trait.Rng.html" title="trait rand::Rng">Rng</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></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/rand/distributions/mod.rs.html#173-212' title='goto source code'>[src]</a></span></h4>
<div class='docblock'><p>Generate a random value.</p>
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