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    <pre><code>dogs = names.zip(breeds).map { |name, breed| Dog.new(name, breed) } </code></pre> <p><code>Array#zip</code> interleaves the target array with elements of the arguments, so</p> <pre><code>irb&gt; [1, 2, 3].zip(['a', 'b', 'c']) #=&gt; [ [1, 'a'], [2, 'b'], [3, 'c'] ] </code></pre> <p>You can use arrays of different lengths (in which case the target array determines the length of the resulting array, with the extra entries filled in with <code>nil</code>).</p> <pre><code>irb&gt; [1, 2, 3, 4, 5].zip(['a', 'b', 'c']) #=&gt; [ [1, 'a'], [2, 'b'], [3, 'c'], [4, nil], [5, nil] ] irb&gt; [1, 2, 3].zip(['a', 'b', 'c', 'd', 'e']) #=&gt; [ [1, 'a'], [2, 'b'], [3, 'c'] ] </code></pre> <p>You can also zip more than two arrays together:</p> <pre><code>irb&gt; [1,2,3].zip(['a', 'b', 'c'], [:alpha, :beta, :gamma]) #=&gt; [ [1, 'a', :alpha], [2, 'b', :beta], [3, 'c', :gamma] ] </code></pre> <p><code>Array#map</code> is a great way to transform an array, since it returns an array where each entry is the result of running the block on the corresponding entry in the target array.</p> <pre><code>irb&gt; [1,2,3].map { |n| 10 - n } #=&gt; [ 9, 8, 7 ] </code></pre> <p>When using iterators over arrays of arrays, if you give a multiple parameter block, the array entries will be automatically broken into those parameters:</p> <pre><code>irb&gt; [ [1, 'a'], [2, 'b'], [3, 'c'] ].each { |array| p array } [ 1, 'a' ] [ 2, 'b' ] [ 3, 'c' ] #=&gt; nil irb&gt; [ [1, 'a'], [2, 'b'], [3, 'c'] ].each do |num, char| ...&gt; puts "number: #{num}, character: #{char}" ...&gt; end number 1, character: a number 2, character: b number 3, character: c #=&gt; [ [1, 'a'], [2, 'b'], [3, 'c'] ] </code></pre> <p>Like <a href="https://stackoverflow.com/users/10771/matt-briggs">Matt Briggs</a> <a href="https://stackoverflow.com/questions/2648824/basic-array-iteration-in-ruby/2648850#2648850">mentioned</a>, <code>#each_with_index</code> is another good tool to know about. It iterates through the elements of an array, passing a block each element in turn.</p> <pre><code>irb&gt; ['a', 'b', 'c'].each_with_index do |char, index| ...&gt; puts "character #{char} at index #{index}" ...&gt; end character a at index 0 character b at index 1 character c at index 2 #=&gt; [ 'a', 'b', 'c' ] </code></pre> <p>When using an iterator like <code>#each_with_index</code> you can use parentheses to break up array elements into their constituent parts:</p> <pre><code>irb&gt; [ [1, 'a'], [2, 'b'], [3, 'c'] ].each_with_index do |(num, char), index| ...&gt; puts "number: #{num}, character: #{char} at index #{index}" ...&gt; end number 1, character: a at index 0 number 2, character: b at index 1 number 3, character: c at index 2 #=&gt; [ [1, 'a'], [2, 'b'], [3, 'c'] ] </code></pre>
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