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            <header><h1><a href="..">Roul</a></h1></header><div class="markdown">
<h1 id="usage"><a href="">Usage</a></h1><p>Roul currently contains a few functions in one namespace.  It'll expand in the
future, but for now that's all it is.</p>
<div class="toc">
<ul><li><a href="#roulrandom">roul.random</a><ul><li><a href="#rand">rand</a></li>
<li><a href="#rand-int">rand-int</a></li>
<li><a href="#rand-nth">rand-nth</a></li>
<li><a href="#rand-nth-weighted">rand-nth-weighted</a></li>
</ul></li>
</ul></div>
<h2 id="roulrandom">roul.random</h2>
<p>The <code>roul.random</code> namespace contains wrappers around some of Clojure's built-in
random functions to make them more user friendly, as well as some uniqe
functions of its own.</p>
<p>The recommended way is to <code>require</code> this namespace into your own instead of
overwriting Clojure's builtins:</p>
<div class="codehilite"><pre><span class="p">(</span><span class="nf">ns</span> <span class="nv">foo</span><span class="o">.</span><span class="nv">core</span>
  <span class="p">(</span><span class="nf">:require</span> <span class="p">[</span><span class="nv">roul</span><span class="o">.</span><span class="nv">random</span> <span class="nv">:as</span> <span class="nv">rr</span><span class="p">]))</span>

<span class="c1">; or</span>

<span class="p">(</span><span class="nf">require</span> <span class="o">'</span><span class="p">[</span><span class="nv">roul</span><span class="o">.</span><span class="nv">random</span> <span class="nv">:as</span> <span class="nv">rr</span><span class="p">])</span>
</pre></div>


<h3 id="rand">rand</h3>
<div class="codehilite"><pre><span class="p">(</span><span class="nf">rand</span><span class="p">)</span>           <span class="c1">; return a float in [0, 1)</span>
<span class="p">(</span><span class="nb">rand </span><span class="nv">end</span><span class="p">)</span>       <span class="c1">; return a float in [0, end)</span>
<span class="p">(</span><span class="nb">rand </span><span class="nv">start</span> <span class="nv">end</span><span class="p">)</span> <span class="c1">; return a float in [start, end)</span>
</pre></div>


<p>A wrapper around the built-in <code>rand</code>.  Returns a random floating point number
between <code>start</code> (inclusive) and <code>end</code> (exclusive).</p>
<p>If not given, <code>start</code> defaults to <code>0</code> and <code>end</code> defaults to <code>1</code>.</p>
<h3 id="rand-int">rand-int</h3>
<div class="codehilite"><pre><span class="p">(</span><span class="nb">rand-int </span><span class="nv">end</span><span class="p">)</span>       <span class="c1">; return an int in [0, end)</span>
<span class="p">(</span><span class="nb">rand-int </span><span class="nv">start</span> <span class="nv">end</span><span class="p">)</span> <span class="c1">; return an int in [start, end)</span>
</pre></div>


<p>A wrapper around the built-in <code>rand-int</code>.  Returns a random integer between
<code>start</code> (inclusive) and <code>end</code> (exclusive).</p>
<p>If not given, <code>start</code> defaults to <code>0</code>.</p>
<h3 id="rand-nth">rand-nth</h3>
<div class="codehilite"><pre><span class="p">(</span><span class="nf">rand-nth</span> <span class="nv">coll</span><span class="p">)</span> <span class="c1">; return a random element of coll</span>
</pre></div>


<p>A wrapper around the built-in <code>rand-nth</code>.  Returns a random element of the given
collection.</p>
<p>This is a transparent wrapper around the builtin, included only for
completeness.  Unlike the other wrappers no new functionality has been added
(yet).</p>
<h3 id="rand-nth-weighted">rand-nth-weighted</h3>
<div class="codehilite"><pre><span class="p">(</span><span class="nf">rand-nth-weighted</span> <span class="nv">coll</span><span class="p">)</span> <span class="c1">; return a random element of coll</span>
</pre></div>


<p>Returns a random element of a weighted collection.</p>
<p>A weighted collection can be any seq of <code>[choice, weight]</code> elements.  The
weights can be arbitrary numbers -- they do not need to add up to anything
specific.</p>
<div class="codehilite"><pre><span class="c1">; Returns coffee roughly 80% of the time, tea 15%, and soda 5%.</span>
<span class="p">(</span><span class="nf">rr/rand-nth-weighted</span> <span class="p">{</span><span class="nv">:coffee</span> <span class="mf">0.80</span><span class="o">,</span> <span class="nv">:tea</span> <span class="mf">0.15</span><span class="o">,</span> <span class="nv">:soda</span> <span class="mf">0.05</span><span class="p">})</span>

<span class="c1">; Returns cats roughly twice as often as boots.</span>
<span class="p">(</span><span class="nf">rr/rand-nth-weighted</span> <span class="p">[[</span><span class="nv">:boots</span> <span class="mi">14</span><span class="p">]</span>
                       <span class="p">[</span><span class="nv">:cats</span> <span class="mi">28</span><span class="p">]])</span>
</pre></div>
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author	Steve Losh <steve@stevelosh.com>
date	Tue, 10 Apr 2012 10:15:03 -0400
parents	3f3e2c21221e
children	9c78e1a01787