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POCalculating heat map colours
 

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  1. POCalculating heat map colours
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    <p>I'm working on a heat map made up of an HTML table. This table contains <em>n</em> cells and has a <em>lowest</em> value and a <em>highest</em> value (highest is always higher than lowest). Each cell has a <em>cell</em> value. All these values are ints.</p> <p>Cells with the lowest value are meant to be a light blue, scaling across to the point where the cells with the highest value are a deep red. See gradient below for an ideal range:</p> <p><img src="https://i.stack.imgur.com/9Ve6P.png" alt="enter image description here"></p> <p>To calculate the hex colour value of each individual cell, I look at the <em>lowest</em> and <em>highest</em> values from the table and the cell's <em>total</em> value, passing them into a method that returns the RGB hex, ready to be used with HTML's <em>background-color</em> style.</p> <p>Here is the method so far:</p> <pre><code>public string ConvertTotalToRgb(int low, int high, int cell) { int range = high - low; int main = 255 * cell/ range; string hexR = main.ToString("X2"); int flip = 255 * (1 - (cell/ range)); string hexB = flip.ToString("X2"); return hexR + "00" + hexB; } </code></pre> <p>With a <em>lowest</em> value of 0 and a <em>highest</em> value of 235, this method returns the following table (cell values are in the cells).</p> <p><img src="https://i.stack.imgur.com/cFKrv.png" alt="enter image description here"></p> <p>Example case: If <em>lowest</em> was 20, <em>highest</em> was 400 and <em>cell</em> was 60, I would want the method returning the RGB hex of the colour about 15.8% of the way along the gradient.</p> <pre><code>400 - 20 = 380 380 / 60 = 6.33 100 / 6.33 = 15.8 </code></pre> <p>I'm aware that this formula isn't quite accurate but that's partially why I'm asking for help here.</p> <p>I've made it this far but I'm really not sure how to proceed. Any help is hugely appreciated!</p>
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    1. COYour question is really confusing.. what does the HTML table look like?
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      1. USSayse
    2. COI literally put a picture of the table in the question, right at the bottom :/
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    3. COI misunderstood then.. where are the values coming from?
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