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  1. PO
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    <p>I have what I believe to be the start of the answer here. </p> <p>I'm looping through the $query and using unset() on each object as it's added to arrays within $result. </p> <p>Hopefully what's written here is as efficient as possible:</p> <pre><code>function cmp($a, $b){ return strcmp($a['start'], $b['start']); } $query = array(array('name' =&gt;'A','start' =&gt;'1/1/2011','end' =&gt;'1/31/2011'),array('name' =&gt;'B','start' =&gt;'1/15/2011','end' =&gt;'1/31/2011'),array('name' =&gt;'C','start' =&gt;'2/1/2011','end' =&gt;'2/28/2011'),array('name' =&gt;'D','start' =&gt;'2/2/2011','end' =&gt;'2/28/2011'),array('name' =&gt;'E','start' =&gt;'1/31/2011','end' =&gt;'3/1/2011'), array('name' =&gt;'F','start' =&gt;'3/3/2011','end' =&gt;'3/31/2011')); usort($query, "cmp"); // organize by start date $result = array(); $c = count($query); for($i = 1; $i &lt;= $c; $i++) { if (empty($result)) { $result[0][0] = $query[0]; unset($query[0]); $query = array_values($query); } else { $lastkey_group = array_pop(array_keys($result)); $lastkey_object = array_pop(array_keys($result[$lastkey_group])); // get the last object's end date $last_end_date = strtotime($result[$lastkey_group][$lastkey_object]['end']); $match_days = 1000; $match_key = 1000; foreach($query as $key =&gt; $q) { $this_start_date = strtotime($q['start']); $diff = round(($this_start_date - $last_end_date)/86400); // compare to start date in each $q if($diff &lt; $match_days &amp;&amp; $diff &gt;= 0) { // if the distance is greater than 0 but less than $diff, // replace match with distance and row key $match_days = $diff; $match_key = $key; } } if($match_key == 1000) { $result[$lastkey_group + 1][0] = $query[0]; // no good matches. write to a new group unset($query[0]); $query = array_values($query); } else { $result[$lastkey_group][$lastkey_object + 1] = $query[$match_key]; // match. write to this group unset($query[$match_key]); $query = array_values($query); } } } var_dump($result); </code></pre> <p>And here's the output of this:</p> <pre><code>array(3) { [0]=&gt; array(3) { [0]=&gt; array(3) { ["name"]=&gt; string(1) "A" ["start"]=&gt; string(8) "1/1/2011" ["end"]=&gt; string(9) "1/31/2011" } [1]=&gt; array(3) { ["name"]=&gt; string(1) "E" ["start"]=&gt; string(9) "1/31/2011" ["end"]=&gt; string(8) "3/1/2011" } [2]=&gt; array(3) { ["name"]=&gt; string(1) "F" ["start"]=&gt; string(8) "3/3/2011" ["end"]=&gt; string(9) "3/31/2011" } } [1]=&gt; array(2) { [0]=&gt; array(3) { ["name"]=&gt; string(1) "B" ["start"]=&gt; string(9) "1/15/2011" ["end"]=&gt; string(9) "1/31/2011" } [1]=&gt; array(3) { ["name"]=&gt; string(1) "C" ["start"]=&gt; string(8) "2/1/2011" ["end"]=&gt; string(9) "2/28/2011" } } [2]=&gt; array(1) { [0]=&gt; array(3) { ["name"]=&gt; string(1) "D" ["start"]=&gt; string(8) "2/2/2011" ["end"]=&gt; string(9) "2/28/2011" } } } </code></pre>
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    1. POWhat's the best logic for grouping objects by closest start and end dates?
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    1. USTJ Nicolaides
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    1. POWhat's the best logic for grouping objects by closest start and end dates?
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