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POjs - How to change one key's value based on another key's value in array of objects
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  1. POjs - How to change one key's value based on another key's value in array of objects
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    copied!<p>I have an array of objects like this:</p> <pre><code>var chartData = [{count: 0, idTag: "24"} {count: 0, idTag: "25"} {count: 0, idTag: "26"}] </code></pre> <p>My code does some work and generates a number (<code>totalValue</code>). If <code>totalValue</code> matches the <code>idTag</code>, its <code>count</code> gets increased by one:</p> <pre><code>for (i=0; i&lt;timesFlipped; i++) { totalValue = runTrial(); for (j=0; j&lt;chartData.length; j++) { if (chartData[j].idTag === totalValue) { chartData[j].count += 1; break; } } } </code></pre> <p>This is a simple example, but <code>chartData</code> could hold a few dozen objects, and <code>timesFlipped</code> can be hundreds of thousands of iterations.</p> <p>Is this the best way to change the <code>count</code> value based on matching the <code>idTag</code> value? Is there a way to just find the index of the array with the correct <code>idTag</code> value without iterating over the whole array of objects?</p> <p>Here's the page I'm working on if you want more context: <a href="http://blue.butler.edu/~aazman/coupling/" rel="nofollow">http://blue.butler.edu/~aazman/coupling/</a></p> <hr> <p><strong>Update:</strong></p> <p>Thanks for all the suggestions. I kinda formed my own solution based on what I saw. A bit more background about the project which led me to my solution:</p> <ul> <li>The length of <code>chartData</code> and the min idTag value are calculated based on user inputs when they click submit</li> <li>Once <code>min</code> and <code>length</code> are calculated (thus the max idTag is known), <code>chartData</code> is iteratively initialized:</li> </ul> <p><code>var min = 23-5*numNickel-numPenny; //numNickel &amp; numPenny are the user inputs</code></p> <p><code>var length = 5*(2*numNickel+1)+2*numPenny;</code></p> <p><code>var tempTag = min;</code></p> <p><code>for (j=0;j&lt;length;j++) {</code></p> <p><code>chartData[j] = {count: 0, idTag = tempTag};</code></p> <p><code>tempTag++;</code></p> <p><code>}</code></p> <ul> <li>For reasons particular to the rules of the game, the idTag values (however many there are) are symmetrically centered around <code>idTag:25</code> (e.g. idTags = {24, 25, 26} or idTags = {20,21,22,23,24,25,26,27,28,29,30}. No matter the length of <code>chartData</code>, the length will always be odd and <code>idTag:25</code> will always be the <code>[(chartData.length-1)/2]</code>'th index.</li> </ul> <p>Thus, if the idTags for <code>chartData</code> are <code>{20,21,22,23,24,25,26,27,28,29,30}</code> and if <code>runTrial()</code> gives <code>totalValue = 22</code>, then <code>idTag:22</code> will always be at index <code>(totalValue - min)</code>.</p> <p>So I changed the initialization of chartData and the way the count gets increased to:</p> <pre><code>for (j=0; j&lt;length; j++) { chartData[j] = {count: 0}; //based on what I'm doing with chartData next, I need each index to still be an object } for (i=0; i&lt;timesFlipped; i++) { totalValue = runTrial(); var index = totalValue - min; chartData[index].count++; } </code></pre> <p>So thanks all for your help :)</p>
 

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