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| <span id="516">516</span> |
| <span id="517">517</span> |
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| </pre><pre class="rust"><code><span class="comment">// Copyright 2019 Developers of the Rand project.</span> |
| <span class="comment">//</span> |
| <span class="comment">// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or</span> |
| <span class="comment">// https://www.apache.org/licenses/LICENSE-2.0> or the MIT license</span> |
| <span class="comment">// <LICENSE-MIT or https://opensource.org/licenses/MIT>, at your</span> |
| <span class="comment">// option. This file may not be copied, modified, or distributed</span> |
| <span class="comment">// except according to those terms.</span> |
| |
| <span class="doccomment">//! This module contains an implementation of alias method for sampling random</span> |
| <span class="doccomment">//! indices with probabilities proportional to a collection of weights.</span> |
| |
| <span class="kw">use</span> <span class="ident"><span class="kw">super</span>::WeightedError</span>; |
| <span class="kw">use</span> <span class="kw">crate</span>::{<span class="ident">uniform::SampleUniform</span>, <span class="ident">Distribution</span>, <span class="ident">Uniform</span>}; |
| <span class="kw">use</span> <span class="ident">core::fmt</span>; |
| <span class="kw">use</span> <span class="ident">core::iter::Sum</span>; |
| <span class="kw">use</span> <span class="ident">core::ops</span>::{<span class="ident">Add</span>, <span class="ident">AddAssign</span>, <span class="ident">Div</span>, <span class="ident">DivAssign</span>, <span class="ident">Mul</span>, <span class="ident">MulAssign</span>, <span class="ident">Sub</span>, <span class="ident">SubAssign</span>}; |
| <span class="kw">use</span> <span class="ident">rand::Rng</span>; |
| <span class="kw">use</span> <span class="ident">alloc</span>::{<span class="ident">boxed::Box</span>, <span class="ident">vec</span>, <span class="ident">vec::Vec</span>}; |
| <span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"serde1"</span>)]</span> |
| <span class="kw">use</span> <span class="ident">serde</span>::{<span class="ident">Serialize</span>, <span class="ident">Deserialize</span>}; |
| |
| <span class="doccomment">/// A distribution using weighted sampling to pick a discretely selected item.</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// Sampling a [`WeightedAliasIndex<W>`] distribution returns the index of a randomly</span> |
| <span class="doccomment">/// selected element from the vector used to create the [`WeightedAliasIndex<W>`].</span> |
| <span class="doccomment">/// The chance of a given element being picked is proportional to the value of</span> |
| <span class="doccomment">/// the element. The weights can have any type `W` for which a implementation of</span> |
| <span class="doccomment">/// [`AliasableWeight`] exists.</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// # Performance</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// Given that `n` is the number of items in the vector used to create an</span> |
| <span class="doccomment">/// [`WeightedAliasIndex<W>`], it will require `O(n)` amount of memory.</span> |
| <span class="doccomment">/// More specifically it takes up some constant amount of memory plus</span> |
| <span class="doccomment">/// the vector used to create it and a [`Vec<u32>`] with capacity `n`.</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// Time complexity for the creation of a [`WeightedAliasIndex<W>`] is `O(n)`.</span> |
| <span class="doccomment">/// Sampling is `O(1)`, it makes a call to [`Uniform<u32>::sample`] and a call</span> |
| <span class="doccomment">/// to [`Uniform<W>::sample`].</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// # Example</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// ```</span> |
| <span class="doccomment">/// use rand_distr::WeightedAliasIndex;</span> |
| <span class="doccomment">/// use rand::prelude::*;</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// let choices = vec!['a', 'b', 'c'];</span> |
| <span class="doccomment">/// let weights = vec![2, 1, 1];</span> |
| <span class="doccomment">/// let dist = WeightedAliasIndex::new(weights).unwrap();</span> |
| <span class="doccomment">/// let mut rng = thread_rng();</span> |
| <span class="doccomment">/// for _ in 0..100 {</span> |
| <span class="doccomment">/// // 50% chance to print 'a', 25% chance to print 'b', 25% chance to print 'c'</span> |
| <span class="doccomment">/// println!("{}", choices[dist.sample(&mut rng)]);</span> |
| <span class="doccomment">/// }</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// let items = [('a', 0), ('b', 3), ('c', 7)];</span> |
| <span class="doccomment">/// let dist2 = WeightedAliasIndex::new(items.iter().map(|item| item.1).collect()).unwrap();</span> |
| <span class="doccomment">/// for _ in 0..100 {</span> |
| <span class="doccomment">/// // 0% chance to print 'a', 30% chance to print 'b', 70% chance to print 'c'</span> |
| <span class="doccomment">/// println!("{}", items[dist2.sample(&mut rng)].0);</span> |
| <span class="doccomment">/// }</span> |
| <span class="doccomment">/// ```</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// [`WeightedAliasIndex<W>`]: WeightedAliasIndex</span> |
| <span class="doccomment">/// [`Vec<u32>`]: Vec</span> |
| <span class="doccomment">/// [`Uniform<u32>::sample`]: Distribution::sample</span> |
| <span class="doccomment">/// [`Uniform<W>::sample`]: Distribution::sample</span> |
| <span class="attribute">#[<span class="ident">cfg_attr</span>(<span class="ident">doc_cfg</span>, <span class="ident">doc</span>(<span class="ident">cfg</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"alloc"</span>)))]</span> |
| <span class="attribute">#[<span class="ident">cfg_attr</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"serde1"</span>, <span class="ident">derive</span>(<span class="ident">Serialize</span>, <span class="ident">Deserialize</span>))]</span> |
| <span class="attribute">#[<span class="ident">cfg_attr</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"serde1"</span>, <span class="ident">serde</span>(<span class="ident">bound</span>(<span class="ident">serialize</span> <span class="op">=</span> <span class="string">"W: Serialize, W::Sampler: Serialize"</span>)))]</span> |
| <span class="attribute">#[<span class="ident">cfg_attr</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"serde1"</span>, <span class="ident">serde</span>(<span class="ident">bound</span>(<span class="ident">deserialize</span> <span class="op">=</span> <span class="string">"W: Deserialize<'de>, W::Sampler: Deserialize<'de>"</span>)))]</span> |
| <span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">WeightedAliasIndex</span><span class="op"><</span><span class="ident">W</span>: <span class="ident">AliasableWeight</span><span class="op">></span> { |
| <span class="ident">aliases</span>: <span class="ident">Box</span><span class="op"><</span>[<span class="ident">u32</span>]<span class="op">></span>, |
| <span class="ident">no_alias_odds</span>: <span class="ident">Box</span><span class="op"><</span>[<span class="ident">W</span>]<span class="op">></span>, |
| <span class="ident">uniform_index</span>: <span class="ident">Uniform</span><span class="op"><</span><span class="ident">u32</span><span class="op">></span>, |
| <span class="ident">uniform_within_weight_sum</span>: <span class="ident">Uniform</span><span class="op"><</span><span class="ident">W</span><span class="op">></span>, |
| } |
| |
| <span class="kw">impl</span><span class="op"><</span><span class="ident">W</span>: <span class="ident">AliasableWeight</span><span class="op">></span> <span class="ident">WeightedAliasIndex</span><span class="op"><</span><span class="ident">W</span><span class="op">></span> { |
| <span class="doccomment">/// Creates a new [`WeightedAliasIndex`].</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// Returns an error if:</span> |
| <span class="doccomment">/// - The vector is empty.</span> |
| <span class="doccomment">/// - The vector is longer than `u32::MAX`.</span> |
| <span class="doccomment">/// - For any weight `w`: `w < 0` or `w > max` where `max = W::MAX /</span> |
| <span class="doccomment">/// weights.len()`.</span> |
| <span class="doccomment">/// - The sum of weights is zero.</span> |
| <span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">new</span>(<span class="ident">weights</span>: <span class="ident">Vec</span><span class="op"><</span><span class="ident">W</span><span class="op">></span>) -> <span class="prelude-ty">Result</span><span class="op"><</span><span class="self">Self</span>, <span class="ident">WeightedError</span><span class="op">></span> { |
| <span class="kw">let</span> <span class="ident">n</span> <span class="op">=</span> <span class="ident">weights</span>.<span class="ident">len</span>(); |
| <span class="kw">if</span> <span class="ident">n</span> <span class="op">==</span> <span class="number">0</span> { |
| <span class="kw">return</span> <span class="prelude-val">Err</span>(<span class="ident">WeightedError::NoItem</span>); |
| } <span class="kw">else</span> <span class="kw">if</span> <span class="ident">n</span> <span class="op">></span> <span class="ident">::core::u32::MAX</span> <span class="kw">as</span> <span class="ident">usize</span> { |
| <span class="kw">return</span> <span class="prelude-val">Err</span>(<span class="ident">WeightedError::TooMany</span>); |
| } |
| <span class="kw">let</span> <span class="ident">n</span> <span class="op">=</span> <span class="ident">n</span> <span class="kw">as</span> <span class="ident">u32</span>; |
| |
| <span class="kw">let</span> <span class="ident">max_weight_size</span> <span class="op">=</span> <span class="ident">W::try_from_u32_lossy</span>(<span class="ident">n</span>) |
| .<span class="ident">map</span>(<span class="op">|</span><span class="ident">n</span><span class="op">|</span> <span class="ident">W::MAX</span> <span class="op">/</span> <span class="ident">n</span>) |
| .<span class="ident">unwrap_or</span>(<span class="ident">W::ZERO</span>); |
| <span class="kw">if</span> <span class="op">!</span><span class="ident">weights</span> |
| .<span class="ident">iter</span>() |
| .<span class="ident">all</span>(<span class="op">|</span><span class="kw-2">&</span><span class="ident">w</span><span class="op">|</span> <span class="ident">W::ZERO</span> <span class="op"><</span><span class="op">=</span> <span class="ident">w</span> <span class="op">&&</span> <span class="ident">w</span> <span class="op"><</span><span class="op">=</span> <span class="ident">max_weight_size</span>) |
| { |
| <span class="kw">return</span> <span class="prelude-val">Err</span>(<span class="ident">WeightedError::InvalidWeight</span>); |
| } |
| |
| <span class="comment">// The sum of weights will represent 100% of no alias odds.</span> |
| <span class="kw">let</span> <span class="ident">weight_sum</span> <span class="op">=</span> <span class="ident">AliasableWeight::sum</span>(<span class="ident">weights</span>.<span class="ident">as_slice</span>()); |
| <span class="comment">// Prevent floating point overflow due to rounding errors.</span> |
| <span class="kw">let</span> <span class="ident">weight_sum</span> <span class="op">=</span> <span class="kw">if</span> <span class="ident">weight_sum</span> <span class="op">></span> <span class="ident">W::MAX</span> { |
| <span class="ident">W::MAX</span> |
| } <span class="kw">else</span> { |
| <span class="ident">weight_sum</span> |
| }; |
| <span class="kw">if</span> <span class="ident">weight_sum</span> <span class="op">==</span> <span class="ident">W::ZERO</span> { |
| <span class="kw">return</span> <span class="prelude-val">Err</span>(<span class="ident">WeightedError::AllWeightsZero</span>); |
| } |
| |
| <span class="comment">// `weight_sum` would have been zero if `try_from_lossy` causes an error here.</span> |
| <span class="kw">let</span> <span class="ident">n_converted</span> <span class="op">=</span> <span class="ident">W::try_from_u32_lossy</span>(<span class="ident">n</span>).<span class="ident">unwrap</span>(); |
| |
| <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">no_alias_odds</span> <span class="op">=</span> <span class="ident">weights</span>.<span class="ident">into_boxed_slice</span>(); |
| <span class="kw">for</span> <span class="ident">odds</span> <span class="kw">in</span> <span class="ident">no_alias_odds</span>.<span class="ident">iter_mut</span>() { |
| <span class="kw-2">*</span><span class="ident">odds</span> <span class="kw-2">*</span><span class="op">=</span> <span class="ident">n_converted</span>; |
| <span class="comment">// Prevent floating point overflow due to rounding errors.</span> |
| <span class="kw-2">*</span><span class="ident">odds</span> <span class="op">=</span> <span class="kw">if</span> <span class="kw-2">*</span><span class="ident">odds</span> <span class="op">></span> <span class="ident">W::MAX</span> { <span class="ident">W::MAX</span> } <span class="kw">else</span> { <span class="kw-2">*</span><span class="ident">odds</span> }; |
| } |
| |
| <span class="doccomment">/// This struct is designed to contain three data structures at once,</span> |
| <span class="doccomment">/// sharing the same memory. More precisely it contains two linked lists</span> |
| <span class="doccomment">/// and an alias map, which will be the output of this method. To keep</span> |
| <span class="doccomment">/// the three data structures from getting in each other's way, it must</span> |
| <span class="doccomment">/// be ensured that a single index is only ever in one of them at the</span> |
| <span class="doccomment">/// same time.</span> |
| <span class="kw">struct</span> <span class="ident">Aliases</span> { |
| <span class="ident">aliases</span>: <span class="ident">Box</span><span class="op"><</span>[<span class="ident">u32</span>]<span class="op">></span>, |
| <span class="ident">smalls_head</span>: <span class="ident">u32</span>, |
| <span class="ident">bigs_head</span>: <span class="ident">u32</span>, |
| } |
| |
| <span class="kw">impl</span> <span class="ident">Aliases</span> { |
| <span class="kw">fn</span> <span class="ident">new</span>(<span class="ident">size</span>: <span class="ident">u32</span>) -> <span class="self">Self</span> { |
| <span class="ident">Aliases</span> { |
| <span class="ident">aliases</span>: <span class="macro">vec!</span>[<span class="number">0</span>; <span class="ident">size</span> <span class="kw">as</span> <span class="ident">usize</span>].<span class="ident">into_boxed_slice</span>(), |
| <span class="ident">smalls_head</span>: <span class="ident">::core::u32::MAX</span>, |
| <span class="ident">bigs_head</span>: <span class="ident">::core::u32::MAX</span>, |
| } |
| } |
| |
| <span class="kw">fn</span> <span class="ident">push_small</span>(<span class="kw-2">&mut</span> <span class="self">self</span>, <span class="ident">idx</span>: <span class="ident">u32</span>) { |
| <span class="self">self</span>.<span class="ident">aliases</span>[<span class="ident">idx</span> <span class="kw">as</span> <span class="ident">usize</span>] <span class="op">=</span> <span class="self">self</span>.<span class="ident">smalls_head</span>; |
| <span class="self">self</span>.<span class="ident">smalls_head</span> <span class="op">=</span> <span class="ident">idx</span>; |
| } |
| |
| <span class="kw">fn</span> <span class="ident">push_big</span>(<span class="kw-2">&mut</span> <span class="self">self</span>, <span class="ident">idx</span>: <span class="ident">u32</span>) { |
| <span class="self">self</span>.<span class="ident">aliases</span>[<span class="ident">idx</span> <span class="kw">as</span> <span class="ident">usize</span>] <span class="op">=</span> <span class="self">self</span>.<span class="ident">bigs_head</span>; |
| <span class="self">self</span>.<span class="ident">bigs_head</span> <span class="op">=</span> <span class="ident">idx</span>; |
| } |
| |
| <span class="kw">fn</span> <span class="ident">pop_small</span>(<span class="kw-2">&mut</span> <span class="self">self</span>) -> <span class="ident">u32</span> { |
| <span class="kw">let</span> <span class="ident">popped</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">smalls_head</span>; |
| <span class="self">self</span>.<span class="ident">smalls_head</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">aliases</span>[<span class="ident">popped</span> <span class="kw">as</span> <span class="ident">usize</span>]; |
| <span class="ident">popped</span> |
| } |
| |
| <span class="kw">fn</span> <span class="ident">pop_big</span>(<span class="kw-2">&mut</span> <span class="self">self</span>) -> <span class="ident">u32</span> { |
| <span class="kw">let</span> <span class="ident">popped</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">bigs_head</span>; |
| <span class="self">self</span>.<span class="ident">bigs_head</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">aliases</span>[<span class="ident">popped</span> <span class="kw">as</span> <span class="ident">usize</span>]; |
| <span class="ident">popped</span> |
| } |
| |
| <span class="kw">fn</span> <span class="ident">smalls_is_empty</span>(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="ident">bool</span> { |
| <span class="self">self</span>.<span class="ident">smalls_head</span> <span class="op">==</span> <span class="ident">::core::u32::MAX</span> |
| } |
| |
| <span class="kw">fn</span> <span class="ident">bigs_is_empty</span>(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="ident">bool</span> { |
| <span class="self">self</span>.<span class="ident">bigs_head</span> <span class="op">==</span> <span class="ident">::core::u32::MAX</span> |
| } |
| |
| <span class="kw">fn</span> <span class="ident">set_alias</span>(<span class="kw-2">&mut</span> <span class="self">self</span>, <span class="ident">idx</span>: <span class="ident">u32</span>, <span class="ident">alias</span>: <span class="ident">u32</span>) { |
| <span class="self">self</span>.<span class="ident">aliases</span>[<span class="ident">idx</span> <span class="kw">as</span> <span class="ident">usize</span>] <span class="op">=</span> <span class="ident">alias</span>; |
| } |
| } |
| |
| <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">aliases</span> <span class="op">=</span> <span class="ident">Aliases::new</span>(<span class="ident">n</span>); |
| |
| <span class="comment">// Split indices into those with small weights and those with big weights.</span> |
| <span class="kw">for</span> (<span class="ident">index</span>, <span class="kw-2">&</span><span class="ident">odds</span>) <span class="kw">in</span> <span class="ident">no_alias_odds</span>.<span class="ident">iter</span>().<span class="ident">enumerate</span>() { |
| <span class="kw">if</span> <span class="ident">odds</span> <span class="op"><</span> <span class="ident">weight_sum</span> { |
| <span class="ident">aliases</span>.<span class="ident">push_small</span>(<span class="ident">index</span> <span class="kw">as</span> <span class="ident">u32</span>); |
| } <span class="kw">else</span> { |
| <span class="ident">aliases</span>.<span class="ident">push_big</span>(<span class="ident">index</span> <span class="kw">as</span> <span class="ident">u32</span>); |
| } |
| } |
| |
| <span class="comment">// Build the alias map by finding an alias with big weight for each index with</span> |
| <span class="comment">// small weight.</span> |
| <span class="kw">while</span> <span class="op">!</span><span class="ident">aliases</span>.<span class="ident">smalls_is_empty</span>() <span class="op">&&</span> <span class="op">!</span><span class="ident">aliases</span>.<span class="ident">bigs_is_empty</span>() { |
| <span class="kw">let</span> <span class="ident">s</span> <span class="op">=</span> <span class="ident">aliases</span>.<span class="ident">pop_small</span>(); |
| <span class="kw">let</span> <span class="ident">b</span> <span class="op">=</span> <span class="ident">aliases</span>.<span class="ident">pop_big</span>(); |
| |
| <span class="ident">aliases</span>.<span class="ident">set_alias</span>(<span class="ident">s</span>, <span class="ident">b</span>); |
| <span class="ident">no_alias_odds</span>[<span class="ident">b</span> <span class="kw">as</span> <span class="ident">usize</span>] <span class="op">=</span> |
| <span class="ident">no_alias_odds</span>[<span class="ident">b</span> <span class="kw">as</span> <span class="ident">usize</span>] <span class="op">-</span> <span class="ident">weight_sum</span> <span class="op">+</span> <span class="ident">no_alias_odds</span>[<span class="ident">s</span> <span class="kw">as</span> <span class="ident">usize</span>]; |
| |
| <span class="kw">if</span> <span class="ident">no_alias_odds</span>[<span class="ident">b</span> <span class="kw">as</span> <span class="ident">usize</span>] <span class="op"><</span> <span class="ident">weight_sum</span> { |
| <span class="ident">aliases</span>.<span class="ident">push_small</span>(<span class="ident">b</span>); |
| } <span class="kw">else</span> { |
| <span class="ident">aliases</span>.<span class="ident">push_big</span>(<span class="ident">b</span>); |
| } |
| } |
| |
| <span class="comment">// The remaining indices should have no alias odds of about 100%. This is due to</span> |
| <span class="comment">// numeric accuracy. Otherwise they would be exactly 100%.</span> |
| <span class="kw">while</span> <span class="op">!</span><span class="ident">aliases</span>.<span class="ident">smalls_is_empty</span>() { |
| <span class="ident">no_alias_odds</span>[<span class="ident">aliases</span>.<span class="ident">pop_small</span>() <span class="kw">as</span> <span class="ident">usize</span>] <span class="op">=</span> <span class="ident">weight_sum</span>; |
| } |
| <span class="kw">while</span> <span class="op">!</span><span class="ident">aliases</span>.<span class="ident">bigs_is_empty</span>() { |
| <span class="ident">no_alias_odds</span>[<span class="ident">aliases</span>.<span class="ident">pop_big</span>() <span class="kw">as</span> <span class="ident">usize</span>] <span class="op">=</span> <span class="ident">weight_sum</span>; |
| } |
| |
| <span class="comment">// Prepare distributions for sampling. Creating them beforehand improves</span> |
| <span class="comment">// sampling performance.</span> |
| <span class="kw">let</span> <span class="ident">uniform_index</span> <span class="op">=</span> <span class="ident">Uniform::new</span>(<span class="number">0</span>, <span class="ident">n</span>); |
| <span class="kw">let</span> <span class="ident">uniform_within_weight_sum</span> <span class="op">=</span> <span class="ident">Uniform::new</span>(<span class="ident">W::ZERO</span>, <span class="ident">weight_sum</span>); |
| |
| <span class="prelude-val">Ok</span>(<span class="self">Self</span> { |
| <span class="ident">aliases</span>: <span class="ident">aliases</span>.<span class="ident">aliases</span>, |
| <span class="ident">no_alias_odds</span>, |
| <span class="ident">uniform_index</span>, |
| <span class="ident">uniform_within_weight_sum</span>, |
| }) |
| } |
| } |
| |
| <span class="kw">impl</span><span class="op"><</span><span class="ident">W</span>: <span class="ident">AliasableWeight</span><span class="op">></span> <span class="ident">Distribution</span><span class="op"><</span><span class="ident">usize</span><span class="op">></span> <span class="kw">for</span> <span class="ident">WeightedAliasIndex</span><span class="op"><</span><span class="ident">W</span><span class="op">></span> { |
| <span class="kw">fn</span> <span class="ident">sample</span><span class="op"><</span><span class="ident">R</span>: <span class="ident">Rng</span> <span class="op">+</span> <span class="question-mark">?</span><span class="ident">Sized</span><span class="op">></span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">rng</span>: <span class="kw-2">&mut</span> <span class="ident">R</span>) -> <span class="ident">usize</span> { |
| <span class="kw">let</span> <span class="ident">candidate</span> <span class="op">=</span> <span class="ident">rng</span>.<span class="ident">sample</span>(<span class="self">self</span>.<span class="ident">uniform_index</span>); |
| <span class="kw">if</span> <span class="ident">rng</span>.<span class="ident">sample</span>(<span class="kw-2">&</span><span class="self">self</span>.<span class="ident">uniform_within_weight_sum</span>) <span class="op"><</span> <span class="self">self</span>.<span class="ident">no_alias_odds</span>[<span class="ident">candidate</span> <span class="kw">as</span> <span class="ident">usize</span>] { |
| <span class="ident">candidate</span> <span class="kw">as</span> <span class="ident">usize</span> |
| } <span class="kw">else</span> { |
| <span class="self">self</span>.<span class="ident">aliases</span>[<span class="ident">candidate</span> <span class="kw">as</span> <span class="ident">usize</span>] <span class="kw">as</span> <span class="ident">usize</span> |
| } |
| } |
| } |
| |
| <span class="kw">impl</span><span class="op"><</span><span class="ident">W</span>: <span class="ident">AliasableWeight</span><span class="op">></span> <span class="ident">fmt::Debug</span> <span class="kw">for</span> <span class="ident">WeightedAliasIndex</span><span class="op"><</span><span class="ident">W</span><span class="op">></span> |
| <span class="kw">where</span> |
| <span class="ident">W</span>: <span class="ident">fmt::Debug</span>, |
| <span class="ident">Uniform</span><span class="op"><</span><span class="ident">W</span><span class="op">></span>: <span class="ident">fmt::Debug</span>, |
| { |
| <span class="kw">fn</span> <span class="ident">fmt</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">f</span>: <span class="kw-2">&mut</span> <span class="ident">fmt::Formatter</span>) -> <span class="ident">fmt::Result</span> { |
| <span class="ident">f</span>.<span class="ident">debug_struct</span>(<span class="string">"WeightedAliasIndex"</span>) |
| .<span class="ident">field</span>(<span class="string">"aliases"</span>, <span class="kw-2">&</span><span class="self">self</span>.<span class="ident">aliases</span>) |
| .<span class="ident">field</span>(<span class="string">"no_alias_odds"</span>, <span class="kw-2">&</span><span class="self">self</span>.<span class="ident">no_alias_odds</span>) |
| .<span class="ident">field</span>(<span class="string">"uniform_index"</span>, <span class="kw-2">&</span><span class="self">self</span>.<span class="ident">uniform_index</span>) |
| .<span class="ident">field</span>(<span class="string">"uniform_within_weight_sum"</span>, <span class="kw-2">&</span><span class="self">self</span>.<span class="ident">uniform_within_weight_sum</span>) |
| .<span class="ident">finish</span>() |
| } |
| } |
| |
| <span class="kw">impl</span><span class="op"><</span><span class="ident">W</span>: <span class="ident">AliasableWeight</span><span class="op">></span> <span class="ident">Clone</span> <span class="kw">for</span> <span class="ident">WeightedAliasIndex</span><span class="op"><</span><span class="ident">W</span><span class="op">></span> |
| <span class="kw">where</span> <span class="ident">Uniform</span><span class="op"><</span><span class="ident">W</span><span class="op">></span>: <span class="ident">Clone</span> |
| { |
| <span class="kw">fn</span> <span class="ident">clone</span>(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="self">Self</span> { |
| <span class="self">Self</span> { |
| <span class="ident">aliases</span>: <span class="self">self</span>.<span class="ident">aliases</span>.<span class="ident">clone</span>(), |
| <span class="ident">no_alias_odds</span>: <span class="self">self</span>.<span class="ident">no_alias_odds</span>.<span class="ident">clone</span>(), |
| <span class="ident">uniform_index</span>: <span class="self">self</span>.<span class="ident">uniform_index</span>, |
| <span class="ident">uniform_within_weight_sum</span>: <span class="self">self</span>.<span class="ident">uniform_within_weight_sum</span>.<span class="ident">clone</span>(), |
| } |
| } |
| } |
| |
| <span class="doccomment">/// Trait that must be implemented for weights, that are used with</span> |
| <span class="doccomment">/// [`WeightedAliasIndex`]. Currently no guarantees on the correctness of</span> |
| <span class="doccomment">/// [`WeightedAliasIndex`] are given for custom implementations of this trait.</span> |
| <span class="attribute">#[<span class="ident">cfg_attr</span>(<span class="ident">doc_cfg</span>, <span class="ident">doc</span>(<span class="ident">cfg</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"alloc"</span>)))]</span> |
| <span class="kw">pub</span> <span class="kw">trait</span> <span class="ident">AliasableWeight</span>: |
| <span class="ident">Sized</span> |
| <span class="op">+</span> <span class="ident">Copy</span> |
| <span class="op">+</span> <span class="ident">SampleUniform</span> |
| <span class="op">+</span> <span class="ident">PartialOrd</span> |
| <span class="op">+</span> <span class="ident">Add</span><span class="op"><</span><span class="ident">Output</span> <span class="op">=</span> <span class="self">Self</span><span class="op">></span> |
| <span class="op">+</span> <span class="ident">AddAssign</span> |
| <span class="op">+</span> <span class="ident">Sub</span><span class="op"><</span><span class="ident">Output</span> <span class="op">=</span> <span class="self">Self</span><span class="op">></span> |
| <span class="op">+</span> <span class="ident">SubAssign</span> |
| <span class="op">+</span> <span class="ident">Mul</span><span class="op"><</span><span class="ident">Output</span> <span class="op">=</span> <span class="self">Self</span><span class="op">></span> |
| <span class="op">+</span> <span class="ident">MulAssign</span> |
| <span class="op">+</span> <span class="ident">Div</span><span class="op"><</span><span class="ident">Output</span> <span class="op">=</span> <span class="self">Self</span><span class="op">></span> |
| <span class="op">+</span> <span class="ident">DivAssign</span> |
| <span class="op">+</span> <span class="ident">Sum</span> |
| { |
| <span class="doccomment">/// Maximum number representable by `Self`.</span> |
| <span class="kw">const</span> <span class="ident">MAX</span>: <span class="self">Self</span>; |
| |
| <span class="doccomment">/// Element of `Self` equivalent to 0.</span> |
| <span class="kw">const</span> <span class="ident">ZERO</span>: <span class="self">Self</span>; |
| |
| <span class="doccomment">/// Produce an instance of `Self` from a `u32` value, or return `None` if</span> |
| <span class="doccomment">/// out of range. Loss of precision (where `Self` is a floating point type)</span> |
| <span class="doccomment">/// is acceptable.</span> |
| <span class="kw">fn</span> <span class="ident">try_from_u32_lossy</span>(<span class="ident">n</span>: <span class="ident">u32</span>) -> <span class="prelude-ty">Option</span><span class="op"><</span><span class="self">Self</span><span class="op">></span>; |
| |
| <span class="doccomment">/// Sums all values in slice `values`.</span> |
| <span class="kw">fn</span> <span class="ident">sum</span>(<span class="ident">values</span>: <span class="kw-2">&</span>[<span class="self">Self</span>]) -> <span class="self">Self</span> { |
| <span class="ident">values</span>.<span class="ident">iter</span>().<span class="ident">copied</span>().<span class="ident">sum</span>() |
| } |
| } |
| |
| <span class="macro">macro_rules!</span> <span class="ident">impl_weight_for_float</span> { |
| (<span class="macro-nonterminal">$</span><span class="macro-nonterminal">T</span>: <span class="ident">ident</span>) => { |
| <span class="kw">impl</span> <span class="ident">AliasableWeight</span> <span class="kw">for</span> <span class="macro-nonterminal">$</span><span class="macro-nonterminal">T</span> { |
| <span class="kw">const</span> <span class="ident">MAX</span>: <span class="self">Self</span> <span class="op">=</span> <span class="ident">::core</span>::<span class="macro-nonterminal">$</span><span class="macro-nonterminal">T::MAX</span>; |
| <span class="kw">const</span> <span class="ident">ZERO</span>: <span class="self">Self</span> <span class="op">=</span> <span class="number">0.0</span>; |
| |
| <span class="kw">fn</span> <span class="ident">try_from_u32_lossy</span>(<span class="ident">n</span>: <span class="ident">u32</span>) -> <span class="prelude-ty">Option</span><span class="op"><</span><span class="self">Self</span><span class="op">></span> { |
| <span class="prelude-val">Some</span>(<span class="ident">n</span> <span class="kw">as</span> <span class="macro-nonterminal">$</span><span class="macro-nonterminal">T</span>) |
| } |
| |
| <span class="kw">fn</span> <span class="ident">sum</span>(<span class="ident">values</span>: <span class="kw-2">&</span>[<span class="self">Self</span>]) -> <span class="self">Self</span> { |
| <span class="ident">pairwise_sum</span>(<span class="ident">values</span>) |
| } |
| } |
| }; |
| } |
| |
| <span class="doccomment">/// In comparison to naive accumulation, the pairwise sum algorithm reduces</span> |
| <span class="doccomment">/// rounding errors when there are many floating point values.</span> |
| <span class="kw">fn</span> <span class="ident">pairwise_sum</span><span class="op"><</span><span class="ident">T</span>: <span class="ident">AliasableWeight</span><span class="op">></span>(<span class="ident">values</span>: <span class="kw-2">&</span>[<span class="ident">T</span>]) -> <span class="ident">T</span> { |
| <span class="kw">if</span> <span class="ident">values</span>.<span class="ident">len</span>() <span class="op"><</span><span class="op">=</span> <span class="number">32</span> { |
| <span class="ident">values</span>.<span class="ident">iter</span>().<span class="ident">copied</span>().<span class="ident">sum</span>() |
| } <span class="kw">else</span> { |
| <span class="kw">let</span> <span class="ident">mid</span> <span class="op">=</span> <span class="ident">values</span>.<span class="ident">len</span>() <span class="op">/</span> <span class="number">2</span>; |
| <span class="kw">let</span> (<span class="ident">a</span>, <span class="ident">b</span>) <span class="op">=</span> <span class="ident">values</span>.<span class="ident">split_at</span>(<span class="ident">mid</span>); |
| <span class="ident">pairwise_sum</span>(<span class="ident">a</span>) <span class="op">+</span> <span class="ident">pairwise_sum</span>(<span class="ident">b</span>) |
| } |
| } |
| |
| <span class="macro">macro_rules!</span> <span class="ident">impl_weight_for_int</span> { |
| (<span class="macro-nonterminal">$</span><span class="macro-nonterminal">T</span>: <span class="ident">ident</span>) => { |
| <span class="kw">impl</span> <span class="ident">AliasableWeight</span> <span class="kw">for</span> <span class="macro-nonterminal">$</span><span class="macro-nonterminal">T</span> { |
| <span class="kw">const</span> <span class="ident">MAX</span>: <span class="self">Self</span> <span class="op">=</span> <span class="ident">::core</span>::<span class="macro-nonterminal">$</span><span class="macro-nonterminal">T::MAX</span>; |
| <span class="kw">const</span> <span class="ident">ZERO</span>: <span class="self">Self</span> <span class="op">=</span> <span class="number">0</span>; |
| |
| <span class="kw">fn</span> <span class="ident">try_from_u32_lossy</span>(<span class="ident">n</span>: <span class="ident">u32</span>) -> <span class="prelude-ty">Option</span><span class="op"><</span><span class="self">Self</span><span class="op">></span> { |
| <span class="kw">let</span> <span class="ident">n_converted</span> <span class="op">=</span> <span class="ident">n</span> <span class="kw">as</span> <span class="self">Self</span>; |
| <span class="kw">if</span> <span class="ident">n_converted</span> <span class="op">></span><span class="op">=</span> <span class="ident"><span class="self">Self</span>::ZERO</span> <span class="op">&&</span> <span class="ident">n_converted</span> <span class="kw">as</span> <span class="ident">u32</span> <span class="op">==</span> <span class="ident">n</span> { |
| <span class="prelude-val">Some</span>(<span class="ident">n_converted</span>) |
| } <span class="kw">else</span> { |
| <span class="prelude-val">None</span> |
| } |
| } |
| } |
| }; |
| } |
| |
| <span class="macro">impl_weight_for_float!</span>(<span class="ident">f64</span>); |
| <span class="macro">impl_weight_for_float!</span>(<span class="ident">f32</span>); |
| <span class="macro">impl_weight_for_int!</span>(<span class="ident">usize</span>); |
| <span class="macro">impl_weight_for_int!</span>(<span class="ident">u128</span>); |
| <span class="macro">impl_weight_for_int!</span>(<span class="ident">u64</span>); |
| <span class="macro">impl_weight_for_int!</span>(<span class="ident">u32</span>); |
| <span class="macro">impl_weight_for_int!</span>(<span class="ident">u16</span>); |
| <span class="macro">impl_weight_for_int!</span>(<span class="ident">u8</span>); |
| <span class="macro">impl_weight_for_int!</span>(<span class="ident">isize</span>); |
| <span class="macro">impl_weight_for_int!</span>(<span class="ident">i128</span>); |
| <span class="macro">impl_weight_for_int!</span>(<span class="ident">i64</span>); |
| <span class="macro">impl_weight_for_int!</span>(<span class="ident">i32</span>); |
| <span class="macro">impl_weight_for_int!</span>(<span class="ident">i16</span>); |
| <span class="macro">impl_weight_for_int!</span>(<span class="ident">i8</span>); |
| |
| <span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">test</span>)]</span> |
| <span class="kw">mod</span> <span class="ident">test</span> { |
| <span class="kw">use</span> <span class="kw">super</span>::<span class="kw-2">*</span>; |
| |
| <span class="attribute">#[<span class="ident">test</span>]</span> |
| <span class="attribute">#[<span class="ident">cfg_attr</span>(<span class="ident">miri</span>, <span class="ident">ignore</span>)]</span> <span class="comment">// Miri is too slow</span> |
| <span class="kw">fn</span> <span class="ident">test_weighted_index_f32</span>() { |
| <span class="ident">test_weighted_index</span>(<span class="ident">f32::into</span>); |
| |
| <span class="comment">// Floating point special cases</span> |
| <span class="macro">assert_eq!</span>( |
| <span class="ident">WeightedAliasIndex::new</span>(<span class="macro">vec!</span>[<span class="ident">::core::f32::INFINITY</span>]).<span class="ident">unwrap_err</span>(), |
| <span class="ident">WeightedError::InvalidWeight</span> |
| ); |
| <span class="macro">assert_eq!</span>( |
| <span class="ident">WeightedAliasIndex::new</span>(<span class="macro">vec!</span>[<span class="op">-</span><span class="number">0_f32</span>]).<span class="ident">unwrap_err</span>(), |
| <span class="ident">WeightedError::AllWeightsZero</span> |
| ); |
| <span class="macro">assert_eq!</span>( |
| <span class="ident">WeightedAliasIndex::new</span>(<span class="macro">vec!</span>[<span class="op">-</span><span class="number">1_f32</span>]).<span class="ident">unwrap_err</span>(), |
| <span class="ident">WeightedError::InvalidWeight</span> |
| ); |
| <span class="macro">assert_eq!</span>( |
| <span class="ident">WeightedAliasIndex::new</span>(<span class="macro">vec!</span>[<span class="op">-</span><span class="ident">::core::f32::INFINITY</span>]).<span class="ident">unwrap_err</span>(), |
| <span class="ident">WeightedError::InvalidWeight</span> |
| ); |
| <span class="macro">assert_eq!</span>( |
| <span class="ident">WeightedAliasIndex::new</span>(<span class="macro">vec!</span>[<span class="ident">::core::f32::NAN</span>]).<span class="ident">unwrap_err</span>(), |
| <span class="ident">WeightedError::InvalidWeight</span> |
| ); |
| } |
| |
| <span class="attribute">#[<span class="ident">test</span>]</span> |
| <span class="attribute">#[<span class="ident">cfg_attr</span>(<span class="ident">miri</span>, <span class="ident">ignore</span>)]</span> <span class="comment">// Miri is too slow</span> |
| <span class="kw">fn</span> <span class="ident">test_weighted_index_u128</span>() { |
| <span class="ident">test_weighted_index</span>(<span class="op">|</span><span class="ident">x</span>: <span class="ident">u128</span><span class="op">|</span> <span class="ident">x</span> <span class="kw">as</span> <span class="ident">f64</span>); |
| } |
| |
| <span class="attribute">#[<span class="ident">test</span>]</span> |
| <span class="attribute">#[<span class="ident">cfg_attr</span>(<span class="ident">miri</span>, <span class="ident">ignore</span>)]</span> <span class="comment">// Miri is too slow</span> |
| <span class="kw">fn</span> <span class="ident">test_weighted_index_i128</span>() { |
| <span class="ident">test_weighted_index</span>(<span class="op">|</span><span class="ident">x</span>: <span class="ident">i128</span><span class="op">|</span> <span class="ident">x</span> <span class="kw">as</span> <span class="ident">f64</span>); |
| |
| <span class="comment">// Signed integer special cases</span> |
| <span class="macro">assert_eq!</span>( |
| <span class="ident">WeightedAliasIndex::new</span>(<span class="macro">vec!</span>[<span class="op">-</span><span class="number">1_i128</span>]).<span class="ident">unwrap_err</span>(), |
| <span class="ident">WeightedError::InvalidWeight</span> |
| ); |
| <span class="macro">assert_eq!</span>( |
| <span class="ident">WeightedAliasIndex::new</span>(<span class="macro">vec!</span>[<span class="ident">::core::i128::MIN</span>]).<span class="ident">unwrap_err</span>(), |
| <span class="ident">WeightedError::InvalidWeight</span> |
| ); |
| } |
| |
| <span class="attribute">#[<span class="ident">test</span>]</span> |
| <span class="attribute">#[<span class="ident">cfg_attr</span>(<span class="ident">miri</span>, <span class="ident">ignore</span>)]</span> <span class="comment">// Miri is too slow</span> |
| <span class="kw">fn</span> <span class="ident">test_weighted_index_u8</span>() { |
| <span class="ident">test_weighted_index</span>(<span class="ident">u8::into</span>); |
| } |
| |
| <span class="attribute">#[<span class="ident">test</span>]</span> |
| <span class="attribute">#[<span class="ident">cfg_attr</span>(<span class="ident">miri</span>, <span class="ident">ignore</span>)]</span> <span class="comment">// Miri is too slow</span> |
| <span class="kw">fn</span> <span class="ident">test_weighted_index_i8</span>() { |
| <span class="ident">test_weighted_index</span>(<span class="ident">i8::into</span>); |
| |
| <span class="comment">// Signed integer special cases</span> |
| <span class="macro">assert_eq!</span>( |
| <span class="ident">WeightedAliasIndex::new</span>(<span class="macro">vec!</span>[<span class="op">-</span><span class="number">1_i8</span>]).<span class="ident">unwrap_err</span>(), |
| <span class="ident">WeightedError::InvalidWeight</span> |
| ); |
| <span class="macro">assert_eq!</span>( |
| <span class="ident">WeightedAliasIndex::new</span>(<span class="macro">vec!</span>[<span class="ident">::core::i8::MIN</span>]).<span class="ident">unwrap_err</span>(), |
| <span class="ident">WeightedError::InvalidWeight</span> |
| ); |
| } |
| |
| <span class="kw">fn</span> <span class="ident">test_weighted_index</span><span class="op"><</span><span class="ident">W</span>: <span class="ident">AliasableWeight</span>, <span class="ident">F</span>: <span class="ident">Fn</span>(<span class="ident">W</span>) -> <span class="ident">f64</span><span class="op">></span>(<span class="ident">w_to_f64</span>: <span class="ident">F</span>) |
| <span class="kw">where</span> <span class="ident">WeightedAliasIndex</span><span class="op"><</span><span class="ident">W</span><span class="op">></span>: <span class="ident">fmt::Debug</span> { |
| <span class="kw">const</span> <span class="ident">NUM_WEIGHTS</span>: <span class="ident">u32</span> <span class="op">=</span> <span class="number">10</span>; |
| <span class="kw">const</span> <span class="ident">ZERO_WEIGHT_INDEX</span>: <span class="ident">u32</span> <span class="op">=</span> <span class="number">3</span>; |
| <span class="kw">const</span> <span class="ident">NUM_SAMPLES</span>: <span class="ident">u32</span> <span class="op">=</span> <span class="number">15000</span>; |
| <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">rng</span> <span class="op">=</span> <span class="ident"><span class="kw">crate</span>::test::rng</span>(<span class="number">0x9c9fa0b0580a7031</span>); |
| |
| <span class="kw">let</span> <span class="ident">weights</span> <span class="op">=</span> { |
| <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">weights</span> <span class="op">=</span> <span class="ident">Vec::with_capacity</span>(<span class="ident">NUM_WEIGHTS</span> <span class="kw">as</span> <span class="ident">usize</span>); |
| <span class="kw">let</span> <span class="ident">random_weight_distribution</span> <span class="op">=</span> <span class="ident">Uniform::new_inclusive</span>( |
| <span class="ident">W::ZERO</span>, |
| <span class="ident">W::MAX</span> <span class="op">/</span> <span class="ident">W::try_from_u32_lossy</span>(<span class="ident">NUM_WEIGHTS</span>).<span class="ident">unwrap</span>(), |
| ); |
| <span class="kw">for</span> <span class="kw">_</span> <span class="kw">in</span> <span class="number">0</span>..<span class="ident">NUM_WEIGHTS</span> { |
| <span class="ident">weights</span>.<span class="ident">push</span>(<span class="ident">rng</span>.<span class="ident">sample</span>(<span class="kw-2">&</span><span class="ident">random_weight_distribution</span>)); |
| } |
| <span class="ident">weights</span>[<span class="ident">ZERO_WEIGHT_INDEX</span> <span class="kw">as</span> <span class="ident">usize</span>] <span class="op">=</span> <span class="ident">W::ZERO</span>; |
| <span class="ident">weights</span> |
| }; |
| <span class="kw">let</span> <span class="ident">weight_sum</span> <span class="op">=</span> <span class="ident">weights</span>.<span class="ident">iter</span>().<span class="ident">copied</span>().<span class="ident">sum</span>::<span class="op"><</span><span class="ident">W</span><span class="op">></span>(); |
| <span class="kw">let</span> <span class="ident">expected_counts</span> <span class="op">=</span> <span class="ident">weights</span> |
| .<span class="ident">iter</span>() |
| .<span class="ident">map</span>(<span class="op">|</span><span class="kw-2">&</span><span class="ident">w</span><span class="op">|</span> <span class="ident">w_to_f64</span>(<span class="ident">w</span>) <span class="op">/</span> <span class="ident">w_to_f64</span>(<span class="ident">weight_sum</span>) <span class="op">*</span> <span class="ident">NUM_SAMPLES</span> <span class="kw">as</span> <span class="ident">f64</span>) |
| .<span class="ident">collect</span>::<span class="op"><</span><span class="ident">Vec</span><span class="op"><</span><span class="ident">f64</span><span class="op">></span><span class="op">></span>(); |
| <span class="kw">let</span> <span class="ident">weight_distribution</span> <span class="op">=</span> <span class="ident">WeightedAliasIndex::new</span>(<span class="ident">weights</span>).<span class="ident">unwrap</span>(); |
| |
| <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">counts</span> <span class="op">=</span> <span class="macro">vec!</span>[<span class="number">0</span>; <span class="ident">NUM_WEIGHTS</span> <span class="kw">as</span> <span class="ident">usize</span>]; |
| <span class="kw">for</span> <span class="kw">_</span> <span class="kw">in</span> <span class="number">0</span>..<span class="ident">NUM_SAMPLES</span> { |
| <span class="ident">counts</span>[<span class="ident">rng</span>.<span class="ident">sample</span>(<span class="kw-2">&</span><span class="ident">weight_distribution</span>)] <span class="op">+</span><span class="op">=</span> <span class="number">1</span>; |
| } |
| |
| <span class="macro">assert_eq!</span>(<span class="ident">counts</span>[<span class="ident">ZERO_WEIGHT_INDEX</span> <span class="kw">as</span> <span class="ident">usize</span>], <span class="number">0</span>); |
| <span class="kw">for</span> (<span class="ident">count</span>, <span class="ident">expected_count</span>) <span class="kw">in</span> <span class="ident">counts</span>.<span class="ident">into_iter</span>().<span class="ident">zip</span>(<span class="ident">expected_counts</span>) { |
| <span class="kw">let</span> <span class="ident">difference</span> <span class="op">=</span> (<span class="ident">count</span> <span class="kw">as</span> <span class="ident">f64</span> <span class="op">-</span> <span class="ident">expected_count</span>).<span class="ident">abs</span>(); |
| <span class="kw">let</span> <span class="ident">max_allowed_difference</span> <span class="op">=</span> <span class="ident">NUM_SAMPLES</span> <span class="kw">as</span> <span class="ident">f64</span> <span class="op">/</span> <span class="ident">NUM_WEIGHTS</span> <span class="kw">as</span> <span class="ident">f64</span> <span class="op">*</span> <span class="number">0.1</span>; |
| <span class="macro">assert!</span>(<span class="ident">difference</span> <span class="op"><</span><span class="op">=</span> <span class="ident">max_allowed_difference</span>); |
| } |
| |
| <span class="macro">assert_eq!</span>( |
| <span class="ident">WeightedAliasIndex</span>::<span class="op"><</span><span class="ident">W</span><span class="op">></span><span class="ident">::new</span>(<span class="macro">vec!</span>[]).<span class="ident">unwrap_err</span>(), |
| <span class="ident">WeightedError::NoItem</span> |
| ); |
| <span class="macro">assert_eq!</span>( |
| <span class="ident">WeightedAliasIndex::new</span>(<span class="macro">vec!</span>[<span class="ident">W::ZERO</span>]).<span class="ident">unwrap_err</span>(), |
| <span class="ident">WeightedError::AllWeightsZero</span> |
| ); |
| <span class="macro">assert_eq!</span>( |
| <span class="ident">WeightedAliasIndex::new</span>(<span class="macro">vec!</span>[<span class="ident">W::MAX</span>, <span class="ident">W::MAX</span>]).<span class="ident">unwrap_err</span>(), |
| <span class="ident">WeightedError::InvalidWeight</span> |
| ); |
| } |
| |
| <span class="attribute">#[<span class="ident">test</span>]</span> |
| <span class="kw">fn</span> <span class="ident">value_stability</span>() { |
| <span class="kw">fn</span> <span class="ident">test_samples</span><span class="op"><</span><span class="ident">W</span>: <span class="ident">AliasableWeight</span><span class="op">></span>(<span class="ident">weights</span>: <span class="ident">Vec</span><span class="op"><</span><span class="ident">W</span><span class="op">></span>, <span class="ident">buf</span>: <span class="kw-2">&mut</span> [<span class="ident">usize</span>], <span class="ident">expected</span>: <span class="kw-2">&</span>[<span class="ident">usize</span>]) { |
| <span class="macro">assert_eq!</span>(<span class="ident">buf</span>.<span class="ident">len</span>(), <span class="ident">expected</span>.<span class="ident">len</span>()); |
| <span class="kw">let</span> <span class="ident">distr</span> <span class="op">=</span> <span class="ident">WeightedAliasIndex::new</span>(<span class="ident">weights</span>).<span class="ident">unwrap</span>(); |
| <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">rng</span> <span class="op">=</span> <span class="ident"><span class="kw">crate</span>::test::rng</span>(<span class="number">0x9c9fa0b0580a7031</span>); |
| <span class="kw">for</span> <span class="ident">r</span> <span class="kw">in</span> <span class="ident">buf</span>.<span class="ident">iter_mut</span>() { |
| <span class="kw-2">*</span><span class="ident">r</span> <span class="op">=</span> <span class="ident">rng</span>.<span class="ident">sample</span>(<span class="kw-2">&</span><span class="ident">distr</span>); |
| } |
| <span class="macro">assert_eq!</span>(<span class="ident">buf</span>, <span class="ident">expected</span>); |
| } |
| |
| <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">buf</span> <span class="op">=</span> [<span class="number">0</span>; <span class="number">10</span>]; |
| <span class="ident">test_samples</span>(<span class="macro">vec!</span>[<span class="number">1i32</span>, <span class="number">1</span>, <span class="number">1</span>, <span class="number">1</span>, <span class="number">1</span>, <span class="number">1</span>, <span class="number">1</span>, <span class="number">1</span>, <span class="number">1</span>], <span class="kw-2">&mut</span> <span class="ident">buf</span>, <span class="kw-2">&</span>[ |
| <span class="number">6</span>, <span class="number">5</span>, <span class="number">7</span>, <span class="number">5</span>, <span class="number">8</span>, <span class="number">7</span>, <span class="number">6</span>, <span class="number">2</span>, <span class="number">3</span>, <span class="number">7</span>, |
| ]); |
| <span class="ident">test_samples</span>(<span class="macro">vec!</span>[<span class="number">0.7f32</span>, <span class="number">0.1</span>, <span class="number">0.1</span>, <span class="number">0.1</span>], <span class="kw-2">&mut</span> <span class="ident">buf</span>, <span class="kw-2">&</span>[ |
| <span class="number">2</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">1</span>, <span class="number">3</span>, |
| ]); |
| <span class="ident">test_samples</span>(<span class="macro">vec!</span>[<span class="number">1.0f64</span>, <span class="number">0.999</span>, <span class="number">0.998</span>, <span class="number">0.997</span>], <span class="kw-2">&mut</span> <span class="ident">buf</span>, <span class="kw-2">&</span>[ |
| <span class="number">2</span>, <span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>, <span class="number">2</span>, <span class="number">1</span>, <span class="number">3</span>, <span class="number">2</span>, <span class="number">1</span>, <span class="number">1</span>, |
| ]); |
| } |
| } |
| </code></pre></div> |
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