NYCPHP Meetup

[Jonathan]

I'll likely use ADODB  as a DB abstraction layer - they even have a C 
module. That should keep my options open.
I like ADODB but I haven't used php's dbx or PEAR db either.
I am not sure if some db features won't be available to me, like certain 
kinds of indexes or table types that I am used to setting in MySQL.
As for Postgres, I fear the complexity a bit.


Kenneth Downs wrote:

>My experience in db servers is limited to MS SQL Server, IBM DB/2 and
>Postgres.  Postgres is the one I pick when the decision is mine.  The
>others I really cannot comment on.
>
>Also, as for the table design, a google search on both web pages and
>newsgroups should yield some pre-existing solutions.
>
>  
>
>>Going off topic:
>>
>>Thinking of ways to persist the graph :
>>I've used MySQL a long time and see them as only getting better. But
>>their dual license deters me from some uses. - what about SQLite - also
>>completely free (LGPL, MIT, or Apache  License I think), small, and fast?
>>Or dbm functions if I only need to store hashes?
>>
>>I'll feel silly if I reinvent the work of the RAP RDF datastore. I'll
>>have to write tests and a couple implementations so I can know what is
>>faster and more efficient.
>>
>>
>>
>>
>>Kenneth Downs wrote:
>>
>>    
>>
>>>Jonathan,
>>>
>>>Glad this helped.
>>>
>>>If your graphs get big then you must do this in a database, don't attempt
>>>it in scripts.
>>>
>>>Many people recommend mySQl because it is free, but PostgreSQL is far
>>>more
>>>capable and is also free.
>>>
>>>
>>>
>>>      
>>>
>>>>Hi Kenneth,
>>>>
>>>>Thanks very much. I like what you have posted!
>>>>I think I would add keys to the arrays and add one more dimension so
>>>>that there can be multiple graphs with the same label.
>>>>
>>>>$arcs['likes'][]  = array('a','a');
>>>>$arcs['likes'][]  = array('a','b');
>>>>$arcs['knows'][]  = array('a','b');
>>>>
>>>>$arcs['knows'][]  = array('b','a');
>>>>$arcs['confusedby'][]  = array('b','a');
>>>>
>>>>I can get the functionality I need from this.
>>>>I wonder how scalable this is. What if there are over 5 million arcs. My
>>>>traversal algorithms would have to be very efficient.
>>>>
>>>>Another package I am looking at for graph manipulation is bundled with
>>>>the PHP RDF package RAP.
>>>>
>>>>http://www.wiwiss.fu-berlin.de/suhl/bizer/rdfapi
>>>>http://www.wiwiss.fu-berlin.de/suhl/bizer/rdfapi/tutorial/usingNamedGraphs.htm#ng-intro
>>>>
>>>>They use quads - where a quad is a labeled graph. In the above data
>>>>structure, a new graph would just be a new set of arcs. So it looks like
>>>>nothing is missing from this array based graph.
>>>>
>>>>Hmm, or why not
>>>>
>>>>$arcs['a']['likes']['b'] = true;
>>>>$arcs['b']['likes']['b'] = false;
>>>>or
>>>>$arcs['b']['likes']['chocolate'][] = '80%';
>>>>$arcs['b']['likes']['chocolate'][] = 'quite significantly';
>>>>
>>>>Then I can have a "triple" with a label and a value.
>>>>
>>>>This could be interesting.
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>Kenneth Downs wrote:
>>>>
>>>>
>>>>
>>>>        
>>>>
>>>>>Johathan,
>>>>>
>>>>>Have you considered putting the nodes into one array, and the arcs into
>>>>>a
>>>>>second?
>>>>>
>>>>>$nodes = array('a'=>array(..info..),'b'=>array(..info..));
>>>>>
>>>>>$arcs = array(array('a','b'),array('b','a'))
>>>>>
>>>>>This allows each node's info to be stored only once, and allows you to
>>>>>then treat the arcs cleanly, allowing or disallowing any combo you may
>>>>>choose.
>>>>>
>>>>>You may have to write a little of your code to walk through things, but
>>>>>you'll have complete integrity and control.
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>          
>>>>>
>>>>>>I'm trying to formulate a question out of this. If there isn't one
>>>>>>here,
>>>>>>I hope the read is interesting.
>>>>>>My goal is to create the simplest efficient graph data structures -
>>>>>>that
>>>>>>allow for cycles.
>>>>>>
>>>>>>The reason one would want cycles in a graph is the following:
>>>>>>a->b
>>>>>>and
>>>>>>b->a
>>>>>>(or b->a again with another arc (also known as a hypergraph))
>>>>>>or
>>>>>>a->a
>>>>>>
>>>>>>where '->' is an arc
>>>>>>Even if the arcs are labled, the data in 'a' is something I don't want
>>>>>>to duplicate.
>>>>>>
>>>>>>I am using php version 4.3.11
>>>>>>
>>>>>>If I try to do this with a simple php array:
>>>>>>
>>>>>>  $a = array();
>>>>>>  $b = array();
>>>>>>
>>>>>>  $a['b'] = & $b;
>>>>>>  $b['a'] = & $a;
>>>>>>
>>>>>>  print_r($a);
>>>>>>
>>>>>>Array
>>>>>>(
>>>>>>  [a] => Array
>>>>>>      (
>>>>>>          [b] => Array
>>>>>>              (
>>>>>>                  [a] => Array
>>>>>>*RECURSION*
>>>>>>              )
>>>>>>
>>>>>>      )
>>>>>>
>>>>>>)
>>>>>>
>>>>>>
>>>>>>I get this recursion error. Or, perhaps this is not an error at all.
>>>>>>But
>>>>>>I can't seem to use this function:
>>>>>>
>>>>>>  function recursive_print($array)
>>>>>>  {
>>>>>>      foreach($array as $key => $value)
>>>>>>      {
>>>>>>          if (is_array($value))
>>>>>>          {
>>>>>>              echo $key .' <hr /> ' .recursive_print($value);
>>>>>>          }
>>>>>>          else
>>>>>>          {
>>>>>>              echo 'end'.$value;
>>>>>>          }
>>>>>>      }
>>>>>>  }
>>>>>>
>>>>>>So I went to the PEAR site -
>>>>>>http://pear.php.net/package/Structures_Graph
>>>>>>This pear package doesn't throw any errors but it also seems to balk
>>>>>>-
>>>>>>although I am not sure the *RECURSION* will affect functionality
>>>>>>
>>>>>>
>>>>>>  include 'Structures/Graph.php';
>>>>>>  $directedGraph =& new Structures_Graph(true);
>>>>>>  $nodeOne =& new Structures_Graph_Node();
>>>>>>  $nodeTwo =& new Structures_Graph_Node();
>>>>>>
>>>>>>
>>>>>>  $directedGraph->addNode(&$nodeOne);
>>>>>>  $directedGraph->addNode(&$nodeTwo);
>>>>>>
>>>>>>
>>>>>>  $nodeOne->connectTo($nodeTwo);
>>>>>>  $nodeTwo->connectTo($nodeOne);
>>>>>>
>>>>>>
>>>>>>Inside the code I found a comment about the Zend engine before the
>>>>>>data
>>>>>>structure procedes to iteratively loop through the the nodes to see if
>>>>>>there are duplicates.
>>>>>>          /*
>>>>>>           ZE1 equality operators choke on the recursive cycle
>>>>>>introduced by the _graph field in the Node object.
>>>>>>           So, we'll check references the hard way
>>>>>>          */
>>>>>>
>>>>>>Even so, print_r produces many recursion warnings.
>>>>>>
>>>>>>Maybe I am just trying to use a hammer for a screwdriver. But can
>>>>>>anyone
>>>>>>offer any insight here?
>>>>>>
>>>>>>Thanks,
>>>>>>
>>>>>>- Jonathan Hendler
>>>>>>
>>>>>>
>>>>>>
>>>>>>_______________________________________________
>>>>>>New York PHP Talk Mailing List
>>>>>>AMP Technology
>>>>>>Supporting Apache, MySQL and PHP
>>>>>>http://lists.nyphp.org/mailman/listinfo/talk
>>>>>>http://www.nyphp.org
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>            
>>>>>>
>>>>>
>>>>>
>>>>>          
>>>>>
>>>>_______________________________________________
>>>>New York PHP Talk Mailing List
>>>>AMP Technology
>>>>Supporting Apache, MySQL and PHP
>>>>http://lists.nyphp.org/mailman/listinfo/talk
>>>>http://www.nyphp.org
>>>>
>>>>
>>>>
>>>>        
>>>>
>>>
>>>
>>>      
>>>
>>_______________________________________________
>>New York PHP Talk Mailing List
>>AMP Technology
>>Supporting Apache, MySQL and PHP
>>http://lists.nyphp.org/mailman/listinfo/talk
>>http://www.nyphp.org
>>
>>    
>>
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