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    <p>First and foremost don't use upper-case letters for variables in Ruby as you did with <code>SomeHash</code> and <code>XPath</code>. When a variable name starts with an upper-case letter, it means it's a constant and you probably didn't want it to be a constant.</p> <p><code>each</code> is not the best way to do this, you can do this much more simply with <code>inject</code> as in:</p> <pre><code>countries = { "Albania"=&gt;"Europe", "Andorra"=&gt;"Europe", "Austria"=&gt;"Europe", "Lebanon"=&gt;"Asia", "Macau"=&gt;"Asia", "Malaysia"=&gt;"Asia", "Papua New Guinea"=&gt;"Asia", "Jamaica"=&gt;"North America", "Martinique"=&gt;"North America", "Argentina"=&gt;"South America", "Chile"=&gt;"South America", "Sao Tome and Principe"=&gt;"Africa", "Senegal"=&gt;"Africa", "Somalia"=&gt;"Africa"} by_continents = countries.inject({}) do |memo, (k,v)| memo[v] ||= [] memo[v] &lt;&lt; k memo end </code></pre> <p>The output for this is:</p> <pre><code>{"Europe"=&gt;["Albania", "Andorra", "Austria"], "Asia"=&gt;["Lebanon", "Macau", "Malaysia", "Papua New Guinea"], "North America"=&gt;["Jamaica", "Martinique"], "South America"=&gt;["Argentina", "Chile"], "Africa"=&gt;["Sao Tome and Principe", "Senegal", "Somalia"]} </code></pre> <p>You have all countries grouped by continent and you can pick any one of them.</p> <p>In your code it should be placed like this:</p> <pre><code>def country inflation_hash = {} XPath.match( data, "//country").map do |element| inflation_hash[element.attributes["name"]] = element.attributes["continent"] end by_continents = inflation_hash.inject({}) do |memo, (k,v)| memo[v] ||= [] memo[v] &lt;&lt; k memo end puts by_continents.inspect by_continents end </code></pre>
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    1. POHow do I summarize hashes within a hash?
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    1. USMaurício Linhares
    1. USMaurício Linhares
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    1. POHow do I summarize hashes within a hash?
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    1. COYou could do it more easily than `inject` using `each_with_object`: `countries.each_with_object({}) do |(k,v), memo|`, and remove the final `memo` in the block.
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      1. USthe Tin Man
    2. CO@theTinMan 's suggestion could be combined with a hash creation that has an empty array as the default value: `countries.each_with_object(Hash.new {|h,k| h[k]=[]}) {|(k,v),memo| memo[v] << k}`.
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      1. USCary Swoveland
    3. COMauricio: thank you for your feedback. Would really like to use your method but unfortunately, it only returns one continent and one country: {"Europe"=>["Albania"]}. @theTinMan: I am working on trying out your method right now. Will let you know how it goes. Thank you everyone for your suggestions! Its all about fine running it now.
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      1. USUzzar
 

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