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  1. PO
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    <p>This is a more complicated example, but better than spaghetti code. Turn your array into XML first.</p> <pre><code>// this is your initial array $my_array = array( array("city"=&gt;309, "store"=&gt;12, "apples"=&gt;21, "oranges"=&gt;14, "lichis"=&gt;34 ), array("city"=&gt;309, "store"=&gt;13, "apples"=&gt;0, "oranges"=&gt;11, "lichis"=&gt;32 ), array("city"=&gt;309, "store"=&gt;14, "apples"=&gt;44, "oranges"=&gt;61, "lichis"=&gt;0 ), array("city"=&gt;309, "store"=&gt;15, "apples"=&gt;7, "oranges"=&gt;0, "lichis"=&gt;6 ), array("city"=&gt;309, "store"=&gt;16, "apples"=&gt;0, "oranges"=&gt;0, "lichis"=&gt;12 ), ); </code></pre> <p>Writing spaghetti code to manually isolate stores becomes a messy jungle of if statements and loops. </p> <pre><code>// might as well convert it to xml function array_to_xml( $data ) { $xml = "&lt;xml&gt;\n"; foreach( $data as $row ) { $xml .= "&lt;entry&gt;"; foreach( $row as $k =&gt; $v ) { $xml .= "&lt;{$k}&gt;{$v}&lt;/{$k}&gt;"; } $xml .= "&lt;/entry&gt;\n"; } $xml .= "&lt;/xml&gt;\n"; return( $xml ); } </code></pre> <p>At this point, <code>$xml</code> looks like this (as a string) and is more manageable:</p> <pre><code>&lt;xml&gt; &lt;entry&gt; &lt;city&gt;309&lt;/city&gt; &lt;store&gt;12&lt;/store&gt; &lt;apples&gt;21&lt;/apples&gt; &lt;oranges&gt;14&lt;/oranges&gt; &lt;lichis&gt;34&lt;/lichis&gt; &lt;/entry&gt; ...(more entries)... &lt;/xml&gt; </code></pre> <p>Now, load it into something queriable with XPath, an XML standard:</p> <pre><code>$xml = simplexml_load_string( array_to_xml( $my_array ) ); </code></pre> <p>To get the count of all the specific fruits in the city (i.e. how many apples, oranges, lichies are there in total in city 309) we need a simple but reusable summary function.</p> <pre><code>// so lets make a generic function to count specific items function count_items( $stores, $items = array() ) { $sum = array(); foreach( $stores as $store ) { foreach( $items as $k ) { if( !isset( $sum[$k] ) ) $sum[$k] = 0; $sum[$k] += $store-&gt;$k; } } return( $sum ); } </code></pre> <p>We only want city 309, and looking specifically for apples, oranges and lichis, since they are fruits:</p> <pre><code>$only_this_city = $xml-&gt;xpath("//entry[city=309]"); print_r( count_items( $only_this_city, array("apples", "oranges", "lichis")) ); </code></pre> <p>We get this:</p> <pre><code>Array ( [apples] =&gt; 72 [oranges] =&gt; 86 [lichis] =&gt; 84 ) </code></pre> <p>Secondly, to grab the values for a specific store:</p> <pre><code>$only_this_store = $xml-&gt;xpath("//entry[city=309 and store=14]"); print_r( count_items( $only_this_store, array("apples") ) ); </code></pre> <p>You get:</p> <pre><code>Array ( [apples] =&gt; 44 ) </code></pre> <p>Obviously you can request more items, or query with more complexity. Look up some docs on XPath for future queries.</p>
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    1. POHow do I count the values of a specific key in a multi-dimensional array in PHP?
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    1. USpp19dd
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    1. COSuch a large supporting structure. I would rather write some spaghetti code with self-explaining element names and plenty of comments. I'm tempted to down-vote; but of course, the OP does not say what the real needs are, and if they are intensive, then a robust solution is the best. Also, it's much better than the infinite cities/fruits array suggestion.
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    2. COAppreciate the comment and restraint, but I wasn't trolling - was being verbose deliberately to point out that sometimes you should focus on code maintenance and reusability instead of the immediate task at hand. IMO, it takes a complex example to point that there are additional benefits to using standardized query methods like XPath.
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    3. COPoints are well presented and intriguing. "Trolling" never crossed my mind (except maybe concerning my own behavior).
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