Tag: graphviz

One of the output formats supported by Yahoo Pipes is a PHP style array. In this post, which describes a way of seeing how well connected a particular Twitter user is to other Twitterers who have recently used a particular hashtag, I’ll show you how it can b used.

The following snippet, (cribbed from Coding Forums) shows how to handle this array:

//Declare the required pipe, specifying the php output
$req = "http://pipes.yahoo.com/ouseful/hashtagtwitterers?_render=php&min=3&n=100&q=%23jiscri";

// Make the request
$phpserialized = file_get_contents($req);

// Parse the serialized response
$phparray = unserialize($phpserialized);

//Here's the raw contents of the array
print_r($phparray);

//Here's how to parse it
foreach ($phparray['value']['items'] AS $key => $val)
	printf("<div><p><a href=\"%s\">%s</a></p><p>%s</p>\n", $val['link'], $val['title'], $val['description']);

The pipe used in the above snippet (http://pipes.yahoo.com/ouseful/hashtagtwitterers) displays a list of people who have recently used a particular hashtag on Twitter a minimum specified number of times.

It’s easy enough to parse out the Twitter ID of each individual, and then for a particular named individual see which of those hashtagging Twitterers they are either following, or are following them. (Why’s this interesting? Well, for any given hashtag community, it can show you how well connected you are with that community).

So let’s see how to do it. First, parse out the Twitter ID:

foreach ($phparray['value']['items'] AS $key => $val) {
	$id=preg_replace("/@([^\s]*)\s.*/", "$1", $val['title']);
	$idList[] = $id; 
}

We have the Twitter screennames, but now we want the actual Twitter user IDs. There are several PHP libraries for accessing the Twitter API. The following relies on an old, rejigged version of the library available from http://github.com/jdp/twitterlibphp/tree/master/twitter.lib.php (the code may need tweaking to work with the current version…), and is really kludged together… (Note to self – tidy this up on day!)

The algorithm is basically as follows, and generates a GraphViz .dot file that will plot the connections a particular user has with the members of a particular hashtagging community:

• get the list of hashtagger Twitter usernames (as above);
• for each username, call the Twitter API to get the corresponding Twitter ID, and print out a label that maps each ID to a username;
• for the user we want to investigate, pull down the list of people who follow them from the Twitter API; for each follower, if the follower is in the hashtaggers set, print out that relationship;
• for the user we want to investigate, pull down the list of people who they follow (i.e. their ‘friends’) from the Twitter API; for each friend, if the friend is in the hashtaggers set, print out that relationship;

$Twitter = new Twitter($myTwitterID, $myTwitterPwd);

//Get the Twitter ID for each user identified by the hashtagger pipe
foreach ($idList as $user) {
	$user_det=$Twitter->showUser($user, 'xml');
 	$p = xml_parser_create();
	xml_parse_into_struct($p,$user_det,$results,$index);
	xml_parser_free($p);
	$id=$results[$index['ID'][0]][value];
	$userID[$user]=$id;
	//print out labels in the Graphviz .dot format
	echo $id."[label=\"".$user."\"];\r";
}

//$userfocus is the Twitter screenname of the person we want to examine
$currUser=$userID[$userfocus];
 
//So who in the hashtagger list is following them?
$follower_det=$Twitter->getFollowers($userfocus, 'xml');
$p = xml_parser_create();
xml_parse_into_struct($p,$follower_det,$results,$index);
xml_parser_free($p);
foreach ($index['ID'] as $item){
	$follower=$results[$item][value];
	//print out edges in the Graphviz .dot format
	if (in_array($follower,$userID)) echo $follower."->".$currUser.";\r";
}

//And who in the hashtagger list are they following?
$friends_det=$Twitter->getFriends($userfocus, 'xml');
$p = xml_parser_create();
xml_parse_into_struct($p,$friends_det,$results,$index);
xml_parser_free($p);
foreach ($index['ID'] as $item){
	$followed=$results[$item][value];
	//print out edges in the Graphviz .dot format
	if (in_array($followed,$userID)) echo $currUser."->".$followed.";\r";
}

For completeness, here are the Twitter object methods and their associated Twitter API calls that were used in the above code:

function showUser($id,$format){
	$api_call=sprintf("http://twitter.com/users/show/%s.%s",$id,$format);
  	return $this->APICall($api_call, false);
}

function getFollowers($id,$format){
  	$api_call=sprintf("http://twitter.com/followers/ids/%s.%s",$id,$format);
 	return $this->APICall($api_call, false);
}
  
function getFriends($id,$format){
  	$api_call=sprintf("http://twitter.com/friends/ids/%s.%s",$id,$format);
 	return $this->APICall($api_call, false);
}

Running the code uses N+2 Twitter API calls, where N is the number of different users identified by the hashtagger pipe.

The output of the script is almost a minimal Graphviz .dot file. All that’s missing is the wrapper, e.g. something like: digraph twitterNet { … }. Here’s what a valid file looks like:

(The labels can appear either before or after the edges – it makes no difference as far as GraphViz is concernd.)

Plotting the graph will show you who the individual of interest is connected to, and how, in the particular hashtag community.

So for example, in the recent #ukoer community, here’s how LornaMCampbell is connected. First a ‘circular’ view:

The arrow direction goes FROM one person TO a person they are following. In the circular diagram, it can be quite hard to see whether a connection is reciprocated or one way.

The Graphviz network diagram uses a separate edge for each connection and makes it easier to spot reciprocated links:

So, there we have it. Another way of looking at Twitter hashtag networks to go along with Preliminary Thoughts on Visualising the OpenEd09 Twitter Network, A Quick Peek at the IWMW2009 Twitter Network and More Thinkses Around Twitter Hashtag Networks: #JISCRI