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<div id="random-initialization" class="section level1">
<h1>Random initialization</h1>
<div class="sourceCode"><pre class="sourceCode python"><code class="sourceCode python"><span class="im">import</span> random
size <span class="op">=</span> <span class="dv">20</span>
numXs <span class="op">=</span> <span class="dv">10</span>
numOs <span class="op">=</span> size<span class="op">-</span>numXs
world <span class="op">=</span> []
world.extend( [<span class="dv">0</span>]<span class="op">*</span>numOs )
world.extend( [<span class="dv">1</span>]<span class="op">*</span>numXs )
random.shuffle(world)
<span class="bu">print</span>(world)</code></pre></div>
<pre><code>[0, 1, 0, 0, 0, 1, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1]</code></pre>
</div>
<div id="prettier-printing" class="section level1">
<h1>Prettier printing</h1>
<div class="sourceCode"><pre class="sourceCode python"><code class="sourceCode python"><span class="kw">def</span> world_as_string(world):
<span class="co">'''Create a string representation</span>
<span class="co"> of object `world` using #s and Os'''</span>
output <span class="op">=</span> <span class="st">''</span>
<span class="cf">for</span> slot <span class="op">in</span> world:
<span class="cf">if</span> slot <span class="op">==</span> <span class="dv">0</span>:
output <span class="op">+=</span> <span class="st">'O'</span>
<span class="cf">else</span>:
output <span class="op">+=</span> <span class="st">'#'</span>
<span class="cf">return</span>(output)
<span class="bu">print</span>(world_as_string(world))</code></pre></div>
<pre><code>O#OOO#OO######OOOO##</code></pre>
</div>
<div id="proportion-of-like-neighbors" class="section level1">
<h1>Proportion of like neighbors</h1>
<div class="sourceCode"><pre class="sourceCode python"><code class="sourceCode python"><span class="kw">def</span> proportion_same(i,world,distance<span class="op">=</span><span class="dv">2</span>):
<span class="co">'''Given a world object and an index `i`, return</span>
<span class="co"> the proportion of world[i]'s neighbors that are</span>
<span class="co"> the same type as world[i] itself.'''</span>
neighbors <span class="op">=</span> []
<span class="co"># get left neighbors</span>
leftIndex <span class="op">=</span> <span class="bu">max</span>(<span class="dv">0</span>,i<span class="op">-</span>distance)
neighbors <span class="op">+=</span> world[leftIndex:i]
<span class="co"># get right neighbors</span>
rightIndex <span class="op">=</span> <span class="bu">min</span>(<span class="bu">len</span>(world),i<span class="op">+</span>distance<span class="dv">+1</span>)
neighbors <span class="op">+=</span> world[i<span class="dv">+1</span>:rightIndex]
num1s <span class="op">=</span> <span class="bu">sum</span>(neighbors)
num0s <span class="op">=</span> <span class="bu">len</span>(neighbors) <span class="op">-</span> num1s
<span class="cf">if</span> world[i]<span class="op">==</span><span class="dv">0</span>:
<span class="cf">return</span>( <span class="bu">float</span>(num0s)<span class="op">/</span>(num0s<span class="op">+</span>num1s) )
<span class="cf">elif</span> world[i]<span class="op">==</span><span class="dv">1</span>:
<span class="cf">return</span>( <span class="bu">float</span>(num1s)<span class="op">/</span>(num0s<span class="op">+</span>num1s) ) </code></pre></div>
</div>
<div id="unhappy-agents" class="section level1">
<h1>Unhappy agents</h1>
<div class="sourceCode"><pre class="sourceCode python"><code class="sourceCode python"><span class="kw">def</span> unhappy_agents(world,threshold<span class="op">=</span>.<span class="dv">5</span>,distance<span class="op">=</span><span class="dv">2</span>):
<span class="co">'''Return a list of indices i for which less than</span>
<span class="co"> `threshold` of world[i]'s neighbors are of the same</span>
<span class="co"> type as world[i] itself'''</span>
unhappy <span class="op">=</span> []
<span class="cf">for</span> i <span class="op">in</span> <span class="bu">range</span>(<span class="bu">len</span>(world)):
<span class="cf">if</span> proportion_same(i,world,distance) <span class="op"><</span> threshold:
unhappy.append(i)
<span class="cf">return</span>(unhappy)</code></pre></div>
</div>
<div id="random-move" class="section level1">
<h1>Random move</h1>
<div class="sourceCode"><pre class="sourceCode python"><code class="sourceCode python"><span class="kw">def</span> randomMove(i,world):
<span class="co">'''move item at index `i` in `world` to a</span>
<span class="co"> random (possibly identical) index'''</span>
agent <span class="op">=</span> world.pop(i)
insertAt <span class="op">=</span> random.randint(<span class="dv">0</span>,<span class="bu">len</span>(world))
world.insert(insertAt,agent)</code></pre></div>
</div>
<div id="putting-it-together" class="section level1">
<h1>Putting it together</h1>
<div class="sourceCode"><pre class="sourceCode python"><code class="sourceCode python"><span class="co"># parameters</span>
threshold <span class="op">=</span> <span class="fl">0.5</span>
nbhd_distance <span class="op">=</span> <span class="dv">5</span>
size <span class="op">=</span> <span class="dv">40</span>
numXs <span class="op">=</span> <span class="dv">20</span>
numOs <span class="op">=</span> size<span class="op">-</span>numXs
world <span class="op">=</span> []
world.extend( [<span class="dv">0</span>]<span class="op">*</span>numOs )
world.extend( [<span class="dv">1</span>]<span class="op">*</span>numXs )
random.shuffle(world)
<span class="cf">while</span> unhappy_agents(world,threshold,nbhd_distance):
<span class="co"># get list of unhappy agents:</span>
cur_unhappy <span class="op">=</span> unhappy_agents(world,threshold,nbhd_distance)
<span class="co"># pick one at random:</span>
index <span class="op">=</span> random.choice(cur_unhappy)
<span class="co"># move that agent to a new slot:</span>
randomMove(index,world)
<span class="bu">print</span>(world_as_string(world))</code></pre></div>
<pre><code>O#OOO#OO#OO####O#O#####OOOOOO#O###O#OO##
O#OOOO#OO#OO####O#O#####OOOOOO#O####OO##
O#OO#OO#OO#OO####O#O####OOOOOO#O####OO##
O#OO#OO#OO#OOO####O#O####OOOOOO#O####O##
O#OO#OOOO##OOO####O#O####OOOOOO#O####O##
O#OOO#OOOO##OOO####O#O####OOOOOO#O######
O#OOOO#OOOO##OO####O#O####OOOOOO#O######
OOOOO#OOOO##OO####O#O#####OOOOOO#O######
OOOOOO#OOOO##OO#####O#####OOOOOO#O######
OOOOOO#OOOO#OO#####O#####OOO#OOO#O######
OOOOOOOOOO#OO#####O#####OOO#O#OO#O######
OOOOOOOOOO#OO#####O######OOOO#OO#O######
OOOO#OOOOOOOO#####O######OOOO#OO#O######
OOOO#OOOOOOOO####O#######OOOO#OO#O######
OOOOOOOO#OOOO####O#######OOOO#OO#O######
OOOOOOOOOOOO####O#######OOOO#OO#O#######
OOOOOOOOOOOO####O#######OOOO#OO#O#######
OOOOOOOOOOOO####O###O####OOO#OO#O#######
OOOOOOOOOOOO####O###O####OOO#OO#O#######
OOOOOOOOOOOO#####O###O####OOOOO#O#######
OOOOOOOOOOOO#####O###O####OOOOO######O##
OOOOOOOOOOOO###O##O###O####OOOO######O##
OOOOOOOOOOOOO###O##O###O####OOO######O##
OOOOOOOOOOOOO###O##OO###O####OOO########
OOOOOOOOOOOOOO###O##O###O####OOO########
OOOOOOOOOOOOOOO###O##O#######OOO########
OOOOOOOOOOOOOOOO#####O#######OOO########
OOOOOOOOOOOOOOOOO#####O#######OO########
OOOOOOOOOOOOOOOOOO#####O#######O########
OOOOOOOOOOOOOOOOOO############OO########
OOOOOOOOOOOOOOOOOO#########O###O########
OOOOOOOOOOOOOOOOOO#######O##O###########
OOOOOOOOOOOOOOOOOOO#########O###########
OOOOOOOOOOOOOOOOOOO###O#################
OOOOOOOOOOO#OOOOOOOO##O#################
OOOOOOOOOOOO#OOOOOOOO###################
OOOO#OOOOOOOOOOOOOOOO###################
OOOOOOOOOOOOOOOOOOOO####################</code></pre>
<div class="sourceCode"><pre class="sourceCode python"><code class="sourceCode python"></code></pre></div>
</div>
<p>This work is licensed under the <a href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC 4.0 Creative Commons License</a>.</p>
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