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POConverting Array of Array of Hashes to Array of Hashes
 

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    <p>I have an array of arrays of hashes.</p> <pre><code>items = [{ "item_9": 152 }, { "item_2": 139 }, { "item_13": 138 }, { "item_72": 137 }, { "item_125": 140 }, { "item_10": 144 }] [{ "item_9": 152 }, { "item_2": 139 }, { "item_13": 138 }, { "item_72": 137 }, { "item_125": 140 }, { "item_10": 146 }] [{ "item_9": 152 }, { "item_2": 139 }, { "item_13": 138 }, { "item_72": 137 }, { "item_125": 140 }, { "item_10": 147 }] [{ "item_9": 152 }, { "item_2": 139 }, { "item_13": 138 }, { "item_72": 137 }, { "item_125": 140 }, { "item_10": 148 }] [{ "item_9": 152 }, { "item_2": 139 }, { "item_13": 138 }, { "item_72": 137 }, { "item_125": 140 }, { "item_10": 153 }] . . . [{ "item_9": 152 }, { "item_2": 145 }, { "item_13": 150 }, { "item_72": 154 }, { "item_125": 141 }, { "item_10": 144 }] [{ "item_9": 152 }, { "item_2": 145 }, { "item_13": 150 }, { "item_72": 154 }, { "item_125": 141 }, { "item_10": 146 }] [{ "item_9": 152 }, { "item_2": 145 }, { "item_13": 150 }, { "item_72": 154 }, { "item_125": 141 }, { "item_10": 147 }] [{ "item_9": 152 }, { "item_2": 145 }, { "item_13": 150 }, { "item_72": 154 }, { "item_125": 141 }, { "item_10": 148 }] [{ "item_9": 152 }, { "item_2": 145 }, { "item_13": 150 }, { "item_72": 154 }, { "item_125": 141 }, { "item_10": 153 }] </code></pre> <p>What I'd like to do is change it to be an array of hashes...</p> <pre><code>items = {"item_9"=&gt;152, "item_2"=&gt;145, "item_13"=&gt;150, "item_72"=&gt;154, "item_125"=&gt;141, "item_10"=&gt;146} {"item_9"=&gt;152, "item_2"=&gt;145, "item_13"=&gt;150, "item_72"=&gt;154, "item_125"=&gt;141, "item_10"=&gt;147} {"item_9"=&gt;152, "item_2"=&gt;145, "item_13"=&gt;150, "item_72"=&gt;154, "item_125"=&gt;141, "item_10"=&gt;148} {"item_9"=&gt;152, "item_2"=&gt;145, "item_13"=&gt;150, "item_72"=&gt;154, "item_125"=&gt;141, "item_10"=&gt;153} </code></pre> <p>I believe I can do this using...</p> <pre><code>items.map! { |item| item.reduce({}, :merge) } </code></pre> <p>However, it's not very performant. At least it's not performant enough when you have 140million records. Is there a better way to do this?</p>
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    1. COThe first I would try: `:update` instead of `:merge` for in-place updates.
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    2. COIt's interesting to note that using for loop does not really help anything.
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