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    <p>Given that you are writing each 8-byte double with 11-12 characters, then the overall memory you need should be around ~450MB, which means the number of items you have should be around 50,000,000.</p> <p>Sorting 50 million values shouldn't take long. What will take long is your <code>for</code> loop where you scan the whole file for every item.</p> <p>A more efficient way would be to sort the file, but keep the duplicate values. Then, all you need is one pass over the file, grouping similar values (or equal values, based on the precision of your histogram) and replace them with a value-count pair.</p> <p>For example, if you have the following file:</p> <pre><code>1 0.6 -2 0 -1 -0.6 0 0 3 </code></pre> <p>After sort you will get:</p> <pre><code>-2 -1 -0.6 0 0 0 0.6 1 3 </code></pre> <p>And if you follow this algorithm:</p> <pre><code>current_bucket = first value in file, floored to histogram_precision bucket_count = 0 for all values v ; write current bucket + additional empty buckets while v &gt; current_bucket + histogram_precision output current_bucket bucket_count current_bucket += histogram precision bucket_count = 0 ; add v to current_bucket bucket_count += 1 </code></pre> <p>given <code>histogram_precision</code> as 1 for example, you will get:</p> <pre><code>-2 1 -1 2 0 4 1 1 2 0 3 1 </code></pre> <p>where each line <code>num count</code> shows the number of values (<code>count</code>) in the range <code>[num, num+histogram_precision)</code>.</p> <p>You may want to use buckets like <code>[0.5, 1.5)</code> for example instead of <code>[1 2)</code>, in which case you should just tweak the first line where the initial bucket is computed, or alternatively change the condition of <code>while</code> loop to <code>v &gt; current_bucket + histogram_precision / 2</code>.</p>
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    1. POStatistically collecting rounding error in a program (C)
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    1. COYou answer is theoretically good, but I was looking for a pratical implementation of it using bash or whatever you like :) Sorry for not being explicit about that.
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    2. COContrary to what you have heard, Stackoverflow isn't a source for free programming. @shahbaz has given you an excellent pseudo-code description of what you need to do. You're welcome to post here follow up questions with sample input, required sample output, code you have created, any error messages and current output from that code with questions about how to resolve your problem.
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    3. CO@AlessandroL., I'm not an `awk` expert, but I believe that algorithm should be as short as what I wrote there if implemented with `awk`. Even in C it wouldn't be more than 15 lines.
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