function compare($str1, $str2)
{
$n1 = strlen($str1);
$n2 = strlen($str2);
$C = LCSLength($str1, $str2);
$subsequence_length = $C[$n1][$n2];
$symdiff = 1.0 - ($n1 + $n2 - 2 * $subsequence_length) / ($n1 + $n2);
return $symdiff;
}
function find_citation($citation, &$result, $threshold = 0.8)
{
global $config;
global $couch;
$q = clean_string($citation);
$rows_per_page = 5;
$url = '/_design/citation/_search/all?q=' . urlencode($q) . '&limit=' . $rows_per_page;
$resp = $couch->send("GET", "/" . $config['couchdb_options']['database'] . "/" . $url);
$obj = json_decode($resp);
if (isset($obj->error)) {
} else {
$result->query_ok = true;
if ($obj->total_rows > 0) {
$best_hit = 0;
$q = strtolower($q);
foreach ($obj->rows as $row) {
$hit = $row->fields->default;
$hit_original = $hit;
$hit = clean_string($hit);
$hit = strtolower($hit);
$query_length = strlen($q);
$hit_length = strlen($hit);
$C = LCSLength($hit, $q);
// length of subsequence as percentage of query string
$subsequence_length = round(100.0 * $C[$hit_length][$query_length] / $query_length);
$symdiff = 1.0 - ($query_length + $hit_length - 2 * $C[$hit_length][$query_length]) / ($query_length + $hit_length);
if ($symdiff > $threshold) {
if ($symdiff >= $best_hit) {
$best_hit = $symdiff;
$match = new stdclass();
$match->text = $citation;
$match->hit = $hit_original;
$match->match = true;
$match->id = $row->id;
$match->score = $row->order[0];
$match->symdiff = $symdiff;
if ($symdiff > $best_hit) {
$result->results = array();
}
$result->results[] = $match;
}
}
}
}
}
return count($result->results) > 1;
}
/**
* @brief Obtain ISSN for a journal
*
* @param journal Journal name
* @param threshold Threshold for matching name (default = 0.75)
*
* If exact match not found we use approximate string matching to find the best match. The
* journal name is stripped of short words ("of", "the") and punctuation, then a MySQL LIKE
* query finds a candidate list. From this list we take title with the best Dice score.
*
* @return ISSN, if it exists, otherwise an empty string
*
*/
function issn_from_journal_title($journal, $threshold = 0.75)
{
global $db;
global $left;
global $right;
global $debug;
$issn = '';
$journal = trim($journal);
// First try and exact match
$sql = 'SELECT * FROM issn WHERE (title = ' . $db->Quote($journal) . ')';
$result = $db->Execute($sql);
if ($result == false) {
die("failed: " . $sql);
}
if ($result->NumRows() == 1) {
$issn = $result->fields['issn'];
} else {
// No exact match, try an approximate match
// Clean up
$query = $journal;
// short pronouns are likely to cause problems as people may get them wrong (ie., "of" and "for")
$query = str_replace(' of ', ' ', $query);
$query = str_replace(' for ', ' ', $query);
$query = preg_replace('/^The /', '', $query);
$query = str_replace('&', 'and', $query);
$query = str_replace(',', '', $query);
$query = str_replace(':', '', $query);
$query = str_replace('\'', '', $query);
$query = str_replace('.', '', $query);
$query = str_replace(' ', '% ', $query);
$query = '%' . $query;
$query .= '%';
$sql = 'SELECT * FROM issn WHERE (title LIKE ' . $db->Quote($query) . ')';
//echo $sql;
$result = $db->Execute($sql);
if ($result == false) {
die("failed: " . $sql);
}
// Build results list
$hits = array();
while (!$result->EOF) {
$left = $right = '';
$qStr = $journal;
$qStr = str_replace('.', '', $qStr);
$hStr = $result->fields['title'];
$hStr = str_replace('.', '', $hStr);
$C = LCSLength($qStr, $hStr);
printDiff($C, $qStr, $hStr, strlen($qStr), strlen($hStr));
$score = $C[strlen($qStr)][strlen($hStr)];
$score = 1.0 - (double) (strlen($qStr) + strlen($hStr) - 2 * $score) / (double) (strlen($qStr) + strlen($hStr));
//$score *= 100;
$hit = array('hit' => $result->fields['title'], 'hitDisplay' => $right, 'score' => $score, 'issn' => $result->fields['issn']);
array_push($hits, $hit);
$result->MoveNext();
}
// sort
$scores = array();
foreach ($hits as $key => $row) {
$scores[$key] = $row['score'];
}
array_multisort($scores, SORT_NUMERIC, SORT_DESC, $hits);
if ($debug) {
echo '<table border="1" cellpadding="2">';
echo '<tr style="font-family:Arial;font-size:12px;"><th>Journal</th><th>Score</th><th>ISSN</th></tr>';
foreach ($hits as $hit) {
echo '<tr style="font-family:Arial;font-size:12px;">';
echo '<td>';
echo "<span style=\"background:white;color:black;\">", $hit['hitDisplay'], "</span>";
echo '</td>';
echo '<td>';
echo $hit['score'];
echo '</td>';
echo '<td>';
echo '<a href="http://journalseek.net/cgi-bin/journalseek/journalsearch.cgi?field=issn&query=' . $hit['issn'] . '" target="_blank">' . $hit['issn'] . '</a>';
echo '</td>';
echo '</tr>';
}
echo '</table>';
}
if (count($hits) > 0) {
// Do we have a hit (above some threshhold)
if ($hits[0]['score'] >= $threshold) {
$issn = $hits[0]['issn'];
}
}
}
return $issn;
}
/**
* @brief Approximate string search for title
*
* Assumes n-gram index available for MySQL, see
* http://iphylo.blogspot.com/2009/10/n-gram-fulltext-indexing-in-mysql.html for details on installing
* this.
*
* @param str Title string to search for
* @param threshold Percentage of str that we require to be in longest common subsequence (default is 75%)
*
* @return Array of matching titles, together with scores
*/
function bhl_title_lookup($str, $threshold = 70)
{
global $db;
$matches = array();
$locs = array();
$str = clean_string($str);
$str_length = strlen($str);
$sql = 'SELECT TitleID, ShortTitle, MATCH(ShortTitle) AGAINST(' . $db->qstr($str) . ')
AS score FROM bhl_title
WHERE MATCH(ShortTitle) AGAINST(' . $db->qstr($str) . ') LIMIT 10';
//echo $sql;
$lcs = array();
$count = 0;
$result = $db->Execute($sql);
if ($result == false) {
die("failed [" . __FILE__ . ":" . __LINE__ . "]: " . $sql);
}
while (!$result->EOF) {
// Get subsequence length
$cleaned_hit = clean_string($result->fields['ShortTitle']);
$cleaned_hit_length = strlen($cleaned_hit);
$C = LCSLength($cleaned_hit, $str);
// length of subsequence as percentage of query string
$subsequence_length = round(100.0 * $C[$cleaned_hit_length][$str_length] / $str_length);
// length of subsequence as percentage of hit
$hit_subsequence_length = round(100.0 * $C[$cleaned_hit_length][$str_length] / $cleaned_hit_length);
//echo $cleaned_hit . ' ' . $subsequence_length . ' ' . $hit_subsequence_length . '<br/>';
if ($subsequence_length >= $threshold && $hit_subsequence_length >= 33) {
array_push($matches, array('TitleID' => $result->fields['TitleID'], 'ShortTitle' => $result->fields['ShortTitle'], 'score' => $result->fields['score'], 'sl' => $subsequence_length, 'subsequence' => $C[$cleaned_hit_length][$str_length], 'x' => $str, 'y' => $cleaned_hit));
array_push($lcs, array('row' => $count, 'subsequence' => $C[$cleaned_hit_length][$str_length]));
}
$count++;
$result->MoveNext();
}
//print_r($lcs);
$scores = array();
$index = array();
foreach ($lcs as $key => $row) {
$scores[$key] = $row['subsequence'];
$index[$key] = $key;
}
array_multisort($scores, SORT_DESC, $index);
//print_r($scores);
//print_r($index);
return $matches;
}
