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copied!<p>** <strong>EDIT</strong> ** : slightly better implementation, now also returns frequences and has a better sequence filter.</p> <pre><code>function getFrequences($input, $minimalSequenceSize = 2) { $sequences = array(); $frequences = array(); $len = count($input); for ($i=0; $i<$len; $i++) { $offset = $i; for ($j=$i+$minimalSequenceSize; $j<$len; $j++) { if ($input[$offset] == $input[$j]) { $sequenceSize = 1; $sequence = array($input[$offset]); while (($offset + $sequenceSize < $j) && ($input[$offset+$sequenceSize] == $input[$j+$sequenceSize])) { if (false !== ($seqIndex = array_search($sequence, $frequences))) { // we already have this sequence, since we found a bigger one, remove the old one array_splice($sequences, $seqIndex, 1); array_splice($frequences, $seqIndex, 1); } $sequence[] = $input[$offset+$sequenceSize]; $sequenceSize++; } if ($sequenceSize >= $minimalSequenceSize) { if (false !== ($seqIndex = array_search($sequence, $sequences))) { $frequences[$seqIndex]++; } else { $sequences[] = $sequence; $frequences[] = 2; // we have two occurances already } // $i += $sequenceSize; // move $i so we don't reuse the same sub-sequence break; } } } } // remove sequences that are sub-sequence of another frequence // ** comment this to keep all sequences regardless ** $len = count($sequences); for ($i=0; $i<$len; $i++) { $freq_i = $sequences[$i]; for ($j=$i+1; $j<$len; $j++) { $freq_j = $sequences[$j]; $freq_inter = array_intersect($freq_i, $freq_j); if (count($freq_inter) != 0) { $len--; if (count($freq_i) > count($freq_j)) { array_splice($sequences, $j, 1); array_splice($frequences, $j, 1); $j--; } else { array_splice($sequences, $i, 1); array_splice($frequences, $i, 1); $i--; break; } } } } return array($sequences, $frequences); }; </code></pre> <p>Test case</p> <pre><code>header('Content-type: text/plain'); $input = array(3, 5, 1, 3, 5, 48, 4, 7, 13, 55, 3, 5, 65, 4, 7, 13, 32, 5, 48, 4, 7, 13); list($sequences, $frequences) = getFrequences($input); foreach ($sequences as $i => $s) { echo "(" . implode(',', $s) . ') f=' . $frequences[$i] . "\n"; } </code></pre> <p>** <strong>EDIT</strong> ** : here's an update to the function. It was almost completely rewritten... tell me if this is what you were looking for. I also added a redundancy check to prevent counting the same sequence, or subsequence, twice.</p> <pre><code>function getFrequences2($input, $minSequenceSize = 2) { $sequences = array(); $last_offset = 0; $last_offset_len = 0; $len = count($input); for ($i=0; $i<$len; $i++) { for ($j=$i+$minSequenceSize; $j<$len; $j++) { if ($input[$i] == $input[$j]) { $offset = 1; $sub = array($input[$i]); while ($i + $offset < $j && $j + $offset < $len) { if ($input[$i + $offset] == $input[$j + $offset]) { array_push($sub, $input[$i + $offset]); } else { break; } $offset++; } $sub_len = count($sub); if ($sub_len >= $minSequenceSize) { // $sub must contain more elements than the last sequence found // otherwise we will count the same sequence twice if ($last_offset + $last_offset_len >= $i + $sub_len) { // we already saw this sequence... ignore continue; } else { // save offset and sub_len for future check $last_offset = $i; $last_offset_len = $sub_len; } foreach ($sequences as & $sequence) { $sequence_len = count($sequence['values']); if ($sequence_len == $sub_len && $sequence['values'] == $sub) { //echo "Found add-full ".var_export($sub, true)." at $i and $j...\n"; $sequence['frequence']++; break 2; } else { if ($sequence_len > $sub_len) { $end = $sequence_len - $sub_len; $values = $sequence['values']; $slice_len = $sub_len; $test = $sub; } else { $end = $sub_len - $sequence_len; $values = $sub; $slice_len = $sequence_len; $test = $sequence['values']; } for ($k=0; $k<=$end; $k++) { if (array_slice($values, $k, $slice_len) == $test) { //echo "Found add-part ".implode(',',$sub)." which is part of ".implode(',',$values)." at $i and $j...\n"; $sequence['values'] = $values; $sequence['frequence']++; break 3; } } } } //echo "Found new ".implode(',',$sub)." at $i and $j...\n"; array_push($sequences, array('values' => $sub, 'frequence' => 2)); break; } } } } return $sequences; }; </code></pre>

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