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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'>−</span>]
</a>
</span><a id='src-531' class='srclink' href='../../src/rand/distributions/mod.rs.html#116-119' title='goto source code'>[src]</a></span></h1>
<pre class='rust struct'>pub struct WeightedChoice<'a, T: 'a> { /* 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>&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'>'a'</span> },
<span class='ident'>Weighted</span> { <span class='ident'>weight</span>: <span class='number'>4</span>, <span class='ident'>item</span>: <span class='string'>'b'</span> },
<span class='ident'>Weighted</span> { <span class='ident'>weight</span>: <span class='number'>1</span>, <span class='ident'>item</span>: <span class='string'>'c'</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'>&</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 'a' 4 times, 'b' 8 and 'c' twice.</span>
<span class='macro'>println</span><span class='macro'>!</span>(<span class='string'>"{}"</span>, <span class='ident'>wc</span>.<span class='ident'>ind_sample</span>(<span class='kw-2'>&</span><span class='kw-2'>mut</span> <span class='ident'>rng</span>));
}<a class='test-arrow' target='_blank' href=''>Run</a></pre>
</div><h2 id='methods'>Methods</h2><h3 class='impl'><span class='in-band'><code>impl<'a, T: <a class='trait' href='https://doc.rust-lang.org/nightly/core/clone/trait.Clone.html' title='core::clone::Clone'>Clone</a>> <a class='struct' href='../../rand/distributions/struct.WeightedChoice.html' title='rand::distributions::WeightedChoice'>WeightedChoice</a><'a, T></code></span><span class='out-of-band'><div class='ghost'></div><a id='src-536' class='srclink' href='../../src/rand/distributions/mod.rs.html#121-155' 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>fn <a href='#method.new' class='fnname'>new</a>(items: <a class='primitive' href='https://doc.rust-lang.org/nightly/std/primitive.slice.html'>&'a mut [</a><a class='struct' href='../../rand/distributions/struct.Weighted.html' title='rand::distributions::Weighted'>Weighted</a><T><a class='primitive' href='https://doc.rust-lang.org/nightly/std/primitive.slice.html'>]</a>) -> <a class='struct' href='../../rand/distributions/struct.WeightedChoice.html' title='rand::distributions::WeightedChoice'>WeightedChoice</a><'a, T></code></span></h4>
<div class='docblock'><p>Create a new <code>WeightedChoice</code>.</p>
<p>Panics if:
- <code>v</code> is empty
- the total weight is 0
- the total weight is larger than a <code>u32</code> can contain.</p>
</div></div><h2 id='implementations'>Trait Implementations</h2><h3 class='impl'><span class='in-band'><code>impl<'a, T: <a class='trait' href='https://doc.rust-lang.org/nightly/core/clone/trait.Clone.html' title='core::clone::Clone'>Clone</a>> <a class='trait' href='../../rand/distributions/trait.Sample.html' title='rand::distributions::Sample'>Sample</a><T> for <a class='struct' href='../../rand/distributions/struct.WeightedChoice.html' title='rand::distributions::WeightedChoice'>WeightedChoice</a><'a, T></code></span><span class='out-of-band'><div class='ghost'></div><a id='src-548' class='srclink' href='../../src/rand/distributions/mod.rs.html#157-159' 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><R: <a class='trait' href='../../rand/trait.Rng.html' title='rand::Rng'>Rng</a>>(&mut self, rng: &mut R) -> T</code></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 class='impl'><span class='in-band'><code>impl<'a, T: <a class='trait' href='https://doc.rust-lang.org/nightly/core/clone/trait.Clone.html' title='core::clone::Clone'>Clone</a>> <a class='trait' href='../../rand/distributions/trait.IndependentSample.html' title='rand::distributions::IndependentSample'>IndependentSample</a><T> for <a class='struct' href='../../rand/distributions/struct.WeightedChoice.html' title='rand::distributions::WeightedChoice'>WeightedChoice</a><'a, T></code></span><span class='out-of-band'><div class='ghost'></div><a id='src-555' class='srclink' href='../../src/rand/distributions/mod.rs.html#161-202' 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><R: <a class='trait' href='../../rand/trait.Rng.html' title='rand::Rng'>Rng</a>>(&self, rng: &mut R) -> T</code></span></h4>
<div class='docblock'><p>Generate a random value.</p>
</div></div></section>
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