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copied!<p><strong>EDIT:</strong> In Ruby 2.1+, you can use <a href="http://www.ruby-doc.org/core-2.1.2/Array.html#method-i-to_h">Array#to_h</a></p> <pre><code>pry(main)> [[:a,:b],[:a,:c],[:c,:b]].to_h => {:a=>:c, :c=>:b} </code></pre> <p><strong>END EDIT</strong></p> <p>The public [] method on the Hash class accepts a key-value pair array and returns a hash with the first element of the array as key and the second as value.</p> <p>The last value in the key-value pair will be the actual value when there are key duplicates.</p> <pre><code>Hash[[[:a,:b],[:a,:c],[:c,:b]]] => {:a=>:c, :c=>:b} </code></pre> <p>This syntax is valid in 1.9.3+ ; I'm not sure about earlier Ruby versions (it's not valid in 1.8.7)</p> <p>ref: <a href="http://www.ruby-doc.org/core-2.1.0/Hash.html#method-c-5B-5D">http://www.ruby-doc.org/core-2.1.0/Hash.html#method-c-5B-5D</a></p> <p>Another interesting way of doing it would be using the inject method: (obviously the method above is more succinct and recommended for this specific problem)</p> <pre><code>[ [:a, :b], [:a, :c], [:c, :b] ].inject({}) { |memo, obj| memo[obj.first] = obj.last memo } => {:a=>:c, :c=>:b} </code></pre> <p>inject iterates over the enumerable, your array in this case, starting with the injected parameter, in this case the empty hash {}.</p> <p>For each object in the enumerable, the block is called with the variables memo and obj:</p> <ul> <li><p>obj is the current object in the array</p></li> <li><p>memo is the value that has been returned by your block's last iteration (for the first iteration, it's what you inject)</p></li> </ul>

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