{

$match = array();

// perform diff, print output

$diff = new Text_Diff($lines1, $lines2);

$line1_count = 0;

$line2_count = 0;

foreach ($diff->_edits as $edit)

{

$edit_type = 1;

if (is_a($edit, 'Text_Diff_Op_copy'))

{

$edit_type = 0;

}

if ($edit_type == 0)

{

// No change, so copy author id across to $author2, and match lines

foreach ($edit->final as $final)

{

$author2[$line2_count] = $author1[$line1_count];

$match[$line1_count] = $line2_count;

$line1_count++;

$line2_count++;

}

}

else

{

// Change

if (is_array($edit->final))

{

foreach ($edit->final as $final)

{

$author2[$line2_count++] = $author2_id;

}

}

if (is_array($edit->orig))

{

$line1_count += count($edit->orig);

}

}

}

// Look for lines that haven't been matched. These may be lines

// that have been moved elsewhere in the text.

// Get sets of line numbers that have been matched

$k1 = array_keys($match);

$k2 = array_values($match);

// Get set of original line numbers

$l1 = array();

for ($i = 0; $i < count($lines1); $i++)

{

$l1[$i] = $i;

}

$l2 = array();

for ($i = 0; $i < count($lines2); $i++)

{

$l2[$i] = $i;

}

// Find unmatched line numbers

$x1 = array_diff($l1, $k1);

$x2 = array_diff($l2, $k2);

// Get text of unmatched lines

$extra1 = array();

$extra2 = array();

foreach ($x1 as $x)

{

$extra1[$x] = $lines1[$x];

}

foreach ($x2 as $x)

{

$extra2[$x] = $lines2[$x];

}

// Go through unmatched lines in first body of text, and look for same text

// in unmatched lines in second body of text. Link identical text together.

foreach ($extra1 as $k => $v)

{

$pos = array_search($v, $extra2);

if ($pos === false)

{

}

else

{

$match[$k] = $pos;

// assign authorship to previous author

$author2[$pos] = $author1[$k];

// We've matched this line so delete from unmatched

unset($extra2[$pos]);

}

}

{

$user_agent = 'rdmpage@gmail.com';

// Get XML history of Wikipedia page

$page_title = str_replace(' ', '_', $page_title);

$xml = get('http://en.wikipedia.org/wiki/Special:Export/' . $page_title . '?history', $user_agent);

if ($xml == '')

{

//die('Didn\'t get XML');

return false;

}

//echo $xml;

// Extra metadata about each revision of this page

$history = xml_edits($xml);

//print_r($history);

if (count($history->edits) == 0)

{

return false;

}

// Texts to compare

$texts = array();

foreach ( $history->edits as $e )

{

array_push($texts, explode("\n", $e->text));

}

// First revision

$start = new stdclass;

$start->authors = array();

$start->match = array();

$start->id = $history->edits[0]->id;

for ($i = 0; $i < count($texts[0]); $i++)

{

$start->authors[$i] = $history->edits[0]->userid;

}

// Get differences between subsequent pairs of revisions

$revisions = array();

$revisions[0] = $start;

$n = count($history->edits);

for ($i = 1; $i < $n; $i++)

{

$revision = new stdclass;

$revision->authors = array();

$revision->match = array();

$revision->id = $history->edits[$i]->id;

$revisions[$i] = $revision;

pairwise_diff($texts[$i-1], $texts[$i],

$revisions[$i-1]->authors, $revisions[$i]->authors, $history->edits[$i]->userid, $revisions[$i-1]->match);

}

/*

foreach ($revisions as $rev)

{

echo "Authors\n";

print_r($rev->authors);

echo "Match\n";

print_r($rev->match);

}

*/

// Generate SVG

$author_colour = array();

$view_width = 1000;

$view_height = 500;

$x = 10;

$y = 20;

// How many revisions?

$num_rev = count($revisions);

$max_lines = 0;

foreach ($texts as $text)

{

$max_lines = max($max_lines, count($text));

}

$x_gap = $view_width / $num_rev;

$x_gap = min(30, $x_gap);

$x_gap = max(1, $x_gap);

$y_gap = $view_height / $max_lines;

$y_gap = min(30, $y_gap);

$y_gap = max(1, $y_gap);

$stroke_width = $x_gap/2;

$stroke_width = max(1, $stroke_width);

$half_stroke = $stroke_width/2;

$svg = '<?xml version="1.0" encoding="UTF-8"?>

<svg xmlns:xlink="http://www.w3.org/1999/xlink"

xmlns="http://www.w3.org/2000/svg"

width="' . $view_width . 'px"

height="' . $view_height . 'px"

>';

foreach ($revisions as $rev)

{

// Get authors in this revision

$a = array();

foreach ($rev->authors as $k => $v)

{

array_push($a, $v);

}

$a = array_unique($a);

// New authors

$n = array_diff($a, array_keys($author_colour));

// Random colour from our range

foreach ($n as $author_id)

{

$author_colour[$author_id] = 'rgb(' . rand(0, 255) . ',' . rand(0, 255) . ',' . rand(0, 255) . ')';

}

// Column representing this edit

$svg .= '<a xlink:href="http://en.wikipedia.org/w/index.php?oldid=' . $rev->id . '" title="Revision ' . $rev->id . '" target="_new" >';

foreach ($rev->authors as $k => $v)

{

$y_pos = $y + ($k * $y_gap);

$svg .= '<path style="stroke:' . $author_colour[$v] . ';stroke-width:' . $stroke_width . ';stroke-linecap:butt;" d="M '

. $x . ' ' . $y_pos . ' ' . $x . ' ' . ($y_pos + $y_gap) . '" />';

}

$svg .= '</a>';

// Draw polygon linking each segement of text in two adjacent revisions

$start_x = $x;

$end_x = $x + $x_gap;

foreach ($rev->match as $k => $v)

{

$start_y = $y + ($k * $y_gap);

$end_y = $y + ($v * $y_gap);

$user_url = '';

if (isset($history->user_name_list[$rev->authors[$k]]))

{

$user_url = 'http://en.wikipedia.org/wiki/User:' . $history->user_name_list[$rev->authors[$k]];

}

else

{

$user_url = 'http://en.wikipedia.org/wiki/Special:Contributions/' . $rev->authors[$k];

}

$svg .= '<a xlink:href="' . $user_url . '" title="Revision ' . $rev->id . '" target="_new" >';

$svg .= '<polygon style="fill:' . $author_colour[$rev->authors[$k]] . ';stroke-width:0;opacity:0.4;" points="'

. ($start_x + $half_stroke) . ', ' . $start_y . ' ' . ($end_x - $half_stroke) . ', ' . $end_y

. ' ' . ($end_x - $half_stroke) . ', ' . ($end_y + $y_gap) . ' ' . ($start_x + $half_stroke) . ', ' . ($start_y + $y_gap)

. ' ' . ($start_x + $half_stroke) . ', ' . $start_y . '" />';

$svg .= '</a>';

}

$x += $x_gap;

}

$svg .= '</svg>';

echo '<!DOCTYPE html>

<html>

<head>

<meta charset="utf-8" />

<title>Wikipedia History Flow</title>

<style type="text/css" title="text/css">

body { font-family: sans-serif; }

</style>

</head>

<body>

<h1>Wikipedia History Flow</h1>';

echo '<p>History flow for Wikipedia page <a href="http://en.wikipedia.org/wiki/' . $page_title . '" target="_new">' . $page_title . '</a> (<a href=".">try another</a>)</p>';

echo '<div style="background-color:rgb(128,128,128);">';

echo $svg;

echo '</div>';

echo '<p>Key:</p>

<ul>

<li>Columns represent revisions of the page (click on a colunn to see that revision)</li>

<li>Rows of text that are the same between revisions are connected by lines coloured by author</li>

<li>Authors are distinguished by colour, click on a line between a column to go to that user\'s Wikipedia page</li>

</ul>';

echo '

<body>

</html>';

return true;

{

echo '<!DOCTYPE html>

<html>

<head>

<title>Wikipedia History Flow</title>

<style type="text/css" title="text/css">

body { font-family: sans-serif; }

</style>

</head>

<body>

<h1>Wikipedia History Flow</h1>

<p><b>Error</b> Couldn\'t get history for page "' . $page_title . '" (<a href=".">try another</a>)</p>

</body>

</html>';

{

echo '<!DOCTYPE html>

<html>

<head>

<title>Wikipedia History Flow</title>

<style type="text/css" title="text/css">

body { font-family: sans-serif; }

</style>

</head>

<body>

<h1>Wikipedia History Flow</h1>

<p>Enter the name of a Wikipedia page (just the name, not the URL) to get a history flow in SVG.</p>

<p><b>Note:</b> Pages with an extensive history of edits will cause this script to run very slowly.</p>

<form action="." method="GET">

<input type="text" name="page" value="">

<input type="Submit" value="Go">

</form>

<p>For background see blog post <a href="http://iphylo.blogspot.com/2009/09/visualising-edit-history-of-wikipedia.html">Visualising edit history of a Wikipedia page</a>. Inspiration came from Jeff Attwood\'s post <a href="http://www.codinghorror.com/blog/archives/001222.html">Mixing Oil and Water: Authorship in a Wiki World</a>, which discusses the <a href="http://researchweb.watson.ibm.com/visual/projects/history_flow/explanation.htm">History Flow project</a>. Makes use of the <a href="http://pear.php.net/package/Text_Diff">Text_Diff</a> package.</p>

<p>By <a href="http://iphylo.blogspot.com/">Rod Page</a></p>

</body>

</html>';

{

$page = '';

// If no query parameters

if (count($_GET) == 0)

{

default_display();

exit(0);

}

if (isset($_GET['page']))

{

$page = $_GET['page'];

$result = display_svg($page);

if (!$result)

{

display_error($page);

}

}

else

{

default_display();

exit(0);

}