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OSM Overpass API with PHP-SimpleXML :: workin with the the OSM-Endpoint

Question

tarifa    0

good day dear programmers, dear experts here at Neowin, 

 

i am currently working on a parser that gets  data via OSM Overpass API with PHP-SimpleXML. I am workin with the pretty new to the work with PHPSimpleXML so do not bear with me for askin newby questions.  I am tryin to get data using Open Street Maps. I want to write a code that works with the endpoint of openstreetmap - and the given data is the starting point for further explorations. My tactic is as follows:

 

I fetch data from the openstreetmap-endpoint 

 

1. i run requests to the openstreetmap-endpoint- (see below) and i try three different APIs per request isn't that easy on ressources and 
2. I don't know how to work with the results that i gather from the OpenStreetmap-Endpoint


see the request: 

 

 

<?php
/**
 * OSM Overpass API with PHP SimpleXML / XPath
 *
 * PHP Version: 5.4 - Can be back-ported to 5.3 by using 5.3 Array-Syntax (not PHP 5.4's square brackets)
 */


//
// 1.) Query an OSM Overpass API Endpoint
//

$query = 'node
  ["amenity"~".*"]
  (38.415938460513274,16.06338500976562,39.52205163048525,17.51220703125);
out;';


This is derived from here: http://stackoverflow.com/questions/16129184/osm-data-parsing-to-get-the-nodes-with-child

I want to filter the data to get the nodes with special category. Here is sample of the OSM data I want to get the whole schools within an area. The first script runs well - but now i want to refine the search and add more tags. Finally i want to store all into the MySQL-db

 

So we need to make some XML parsing with PHP:

The following is a little OSM Overpass API example with PHP SimpleXML

 

 

 

<?php
/**
 * OSM Overpass API with PHP SimpleXML / XPath
 *
 * PHP Version: 5.4 - Can be back-ported to 5.3 by using 5.3 Array-Syntax (not PHP 5.4's square brackets)
 */

//
// 1.) Query an OSM Overpass API Endpoint
//

$query = 'node
  ["amenity"~".*"]
  (38.415938460513274,16.06338500976562,39.52205163048525,17.51220703125);
out;';

$context = stream_context_create(['http' => [
    'method'  => 'POST',
    'header' => ['Content-Type: application/x-www-form-urlencoded'],
    'content' => 'data=' . urlencode($query),
]]);

# please do not stress this service, this example is for demonstration purposes only.
$endpoint = 'http://overpass-api.de/api/interpreter';
libxml_set_streams_context($context);
$start = microtime(true);

$result = simplexml_load_file($endpoint);
printf("Query returned %2\$d node(s) and took %1\$.5f seconds.\n\n", microtime(true) - $start, count($result->node));

//
// 2.) Work with the XML Result
//

# get all school nodes with xpath
$xpath = '//node[tag[@k = "amenity" and @v = "school"]]';
$schools = $result->xpath($xpath);
printf("%d School(s) found:\n", count($schools));
foreach ($schools as $index => $school)
{
    # Get the name of the school (if any), again with xpath
    list($name) = $school->xpath('tag[@k = "name"]/@v') + ['(unnamed)'];
    printf("#%02d: ID:%' -10s  [%s,%s]  %s\n", $index, $school['id'], $school['lat'], $school['lon'], $name);
}

?>

 

The second part is more interesting. That is querying the XML data you have already. This is most easily done with xpath, the used PHP XML library is based on libxml which supports XPath 1.0 which covers the various querying needs very well. The following example lists all schools and tries to obtain their names as well. I have not covered translations yet because my sample data didn't have those, but you can also look for all kind of names including translations and just prefer a specific one):

The key point here are the xpath queries. Two are used, the first one to get the nodes that have certain tags. I think this is the most interesting one for you:

 

//node[tag[@k = "amenity" and @v = "school"]]

 

This line says: Give me all node elements that have a tag element inside which has the k attribute value "amenity" and the v attribute value "school". This is the condition you have to filter out those nodes that are tagged with amenity school. Further on xpath is used again, now relative to those school nodes to see if there is a name and if so to fetch it:

 

tag[@k = "name"]/@v'

 

This line says: Relative to the current node, give me the v attribute from a tag element that as the k attribute value "name". As you can see, some parts are again similar to the line before. I think you can both adopt them to your needs. Because not all school nodes have a name, a default string is provided for display purposes by adding it to the (then empty) result array:

 

list($name) = $school->xpath('tag[@k = "name"]/@v') + ['(unnamed)'];
                                                    ^^^^^^^^^^^^^^^
                                                Provide Default Value

so far so good: note. i need to have the adress-data, of the school with

 

cf http://wiki.openstreetmap.org/wiki/Key:addr

and even more important

cf http://wiki.openstreetmap.org/wiki/Key:contact

 

Quote

contact:phone 
contact:fax     
contact:website 
contact:email

 

btw. here my results for that code-example:

 

 

 

martin@linux-70ce:~/php> 
martin@linux-70ce:~/php> php osm1.php
Query returned 1691 node(s) and took 3.34569 seconds.

23 School(s) found:
#00: ID:332534486   [39.5017565,16.2721899]  Scuola Primaria
#01: ID:1428094278  [39.3320912,16.1862820]  (unnamed)
#02: ID:1822746784  [38.9075566,16.5776597]  (unnamed)
#03: ID:1822755951  [38.9120272,16.5713431]  (unnamed)
#04: ID:1903859699  [38.6830409,16.5522243]  Liceo Scientifico Statale A. Guarasci
#05: ID:2002566438  [39.1349460,16.0736446]  (unnamed)
#06: ID:2056891127  [39.4106679,16.8254844]  (unnamed)
#07: ID:2056892999  [39.4124687,16.8286119]  (unnamed)
#08: ID:2272010226  [39.4481717,16.2894353]  SCUOLA DELL'INFANZIA SAN FRANCESCO
#09: ID:2272017152  [39.4502366,16.2807664]  Scuola Media
#10: ID:2358307794  [39.5015031,16.3905965]  I.I.S.S. Liceo Statale V. Iulia
#11: ID:2358307796  [39.4926280,16.3853662]  Liceo Classico
#12: ID:2358307797  [39.4973761,16.3858275]  Scuola Media
#13: ID:2358307800  [39.5015527,16.3941156]  I.T.C. e per Geometri
#14: ID:2358307801  [39.4983862,16.3807796]  Istituto Professionale
#15: ID:2358344885  [39.4854617,16.3832419]  Istituto Tecnico Statale Commerciale G. Falcone
martin@linux-70ce:~/php>

 

note. i need to have the adress-data, of the shool with

and even more important http://wiki.openstreetmap.org/wiki/Key:contact

 

Quote

contact:phone 
contact:fax     
contact:website 
contact:email
 

 

How to add this .. into the query? and how to finally store all into the MySQL-db?

update: can i rework like so:

 

 

 

$xml = file_get_contents($url);
$data = new SimpleXMLElement($xml);

$data variable contains the following:

SimpleXMLElement Object
(
    [@attributes] => Array
        (
            [timestamp] => Sat, 15 Jun 13 20:02:13 +0000
            [attribution] => Data Š OpenStreetMap contributors, ODbL 1.0. http://www.openstreetmap.org/copyright
            [querystring] => Bucharest-Romania
            [polygon] => false
            [exclude_place_ids] => 331526
            [more_url] => http://nominatim.openstreetmap.org/search?format=xml&exclude_place_ids=331526&q=Bucharest-Romania
        )

    [place] => SimpleXMLElement Object
        (
            [@attributes] => Array
                (
                    [place_id] => 331526
                    [osm_type] => node
                    [osm_id] => 96209423
                    [place_rank] => 15
                    [boundingbox] => 44.4361381530762,44.4361419677734,26.1027431488037,26.1027450561523
                    [lat] => 44.436139
                    [lon] => 26.1027436
                    [display_name] => BucureČti, Sector 2, Bucuresti, România, European Union
                    [class] => place
                    [type] => city
                    [importance] => 0.73231672860554
                    [icon] => http://nominatim.openstreetmap.org/images/mapicons/poi_place_city.p.20.png
                )

        )

)

 

 

dear friends, look forward to hear from you

 

 

Edited by tarifa

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3 answers to this question

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+Human.Online    8,611

You know there are dedicated support forums

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tarifa    0

good day dear +Human.Online, 

 

 

first of all: many thanks for the quick reply. glad to hear from you.  Sure thing - there are various forums out there that are centered and focused on topics like 

 

- OpenStreetmap

- Geospatial-topics

- PHP-forums - with expertise on topics such als Xpath topics and XML-parser 

- Linux-forums that cover all the above topics alltogehter

 

- on a sidenote: i am pretty new to this forum here - but i encountered this forum as being capable to cover all computer-topics - 

so as of now - (with experience of 117 postings) i treat this forum as a one stop contact point - for all computer-things

 

but probably i am wrong with this idea and hypothesis or praxis!? - perhaps i cannot treat this forum as such .... 

 

above all - i love this place as a place for idea sharing and knowledge exchange - generally spoken - for being a universe of discourse for all computer  things.. 

 

generally spoken:  i love this forum for its people that fuel all the discourse and idea exchange. 

 

many thanks for your continued support. + Human.Online

 

 

have a great day 

- Tarifa ;)

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+Human.Online    8,611

But do you not see, you aren’t really getting the responses you seem to need here?

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