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    <p>The for loop is not the best way to approach iterating over an array in Ruby. With the clarification of your question, I think you have a few possibly strategies.</p> <p>You have two arrays, a and b. If both arrays are the same length:</p> <pre><code>a.each_index do |index| if a[index] == b[index] do something else do something else end end </code></pre> <p>This also works if A is shorter than B.</p> <p>If you don't know which one is shorter, you could write something like:</p> <p><code>controlArray = a.length &lt; b.length ? a : b</code> to assign the controlArray, the use controlArray.each_index. Or you could use <code>(0..[a.length, b.length].min).each{|index| ...}</code> to accomplish the same thing.</p> <hr> <p>Looking over your edit to your question, I think I can rephrase it like this: given an array with duplicates, how can I obtain a count of each item in each array and compare the counts? In your case, I think the easiest way to do that would be like this:</p> <pre><code>a = [:a,:a,:a,:b,:b,:c,:c,:d,:e,:e,:e] b = [:a,:a,:b,:b,:b,:c,:c,:c,:d,:e,:e,:e] not_alike = [] a.uniq.each{|value| not_alike &lt;&lt; value if a.count(value) != b.count(value)} not_alike </code></pre> <p>Running that code gives me <code>[:a,:b,:c]</code>. </p> <p>If it is possible that a does not contain every symbol, then you will need to have an array which just contains the symbols and use that instead of a.uniq, and another <code>and</code> statement in the conditional could deal with nil or 0 counts.</p>
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    1. COthe problem with this solution is that there is a common index for both a and b. Please see Edit. Thanks though
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    2. CO@mhz - please see revised answer
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    3. COThanks a bunch for the revised answer. I ended up doing a massive for-loop with 2 different indexes that worked. But your way makes much more sense! Thanks!
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