OSM数据解析以获取带有子节点的节点 [英] OSM Data parsing to get the nodes with child
问题描述
我下载了一个小区域的开放街道地图数据，我想过滤数据以获取具有特殊类别的节点.
I download Open Street Map data for a small region, I want to filter the data to get the nodes with special category.
这是OSM数据的示例
<node id="505126369" lat="31.2933856" lon="34.2687443" user="JumpStart International" uid="125156" visible="true" version="1" changeset="2568758" timestamp="2009-09-22T13:05:10Z"/>
<node id="505126372" lat="31.2682934" lon="34.2745680" user="JumpStart International" uid="125156" visible="true" version="1" changeset="2568758" timestamp="2009-09-22T13:05:10Z"/>
<node id="505126375" lat="31.2953082" lon="34.3471630" user="JumpStart International" uid="125156" visible="true" version="1" changeset="2568758" timestamp="2009-09-22T13:05:10Z"/>
<node id="505126378" lat="31.2807872" lon="34.2757999" user="JumpStart International" uid="125156" visible="true" version="1" changeset="2568758" timestamp="2009-09-22T13:05:11Z">
<tag k="amenity" v="school"/>
<tag k="name" v="Al Aqqad Basic & Secondary Female School"/>
<tag k="name:ar" v="مدرسة العقاد الأساسية والثانوية للبنات"/>
</node>
我想获得整个学校，医院的数据.
I want to get the whole schools, hospitals in the data.
如果有人使用PHP或Java进行XML解析，我将非常感激与我和所有利益分享它.
If anybody had made the XML parsing with PHP or Java, I would highly appreciate sharing it with me and all interests.
修改 这只是我的一个简单开始
Edit Here is a simple start I have just
$dataFile = base_url() . 'media/files/osmdata/map_3.xml';
//echo ($dataFile);
$xml = simplexml_load_file($dataFile);
// $countTotal = count($xml->node);
// echo 'here'.$countTotal;
foreach ($xml as $key => $val) {
var_dump($val);
// can't manage things overs here
}
推荐答案
下面是一个使用PHP SimpleXML的OSM Overpass API示例，我已经编译过了，因为我们在PHP中没有它，而且我喜欢OSM，所以让我们来展示一下一些有用的例子.
The following is a little OSM Overpass API example with PHP SimpleXML I've compiled because we do not have it here for PHP and I love OSM, so let's show some useful examples.
第一部分显示了如何使用标准PHP查询立交端点.您不需要那部分，因为您已经将数据保存在硬盘上:
The first part shows how you can query an Overpass Endpoint with standard PHP. You do not need that part because you have already saved the data on your harddisk:
<?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));
对您来说，第二部分更有趣.那就是查询您已经拥有的XML数据.使用xpath最容易做到这一点，所使用的PHP XML库基于libxml，它支持 XPath 1.0 很好地满足了各种查询需求.
For you 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.
以下示例列出了所有学校，并尝试获取其名称.我还没有介绍翻译，因为我的样本数据没有这些翻译，但是您也可以查找包括翻译在内的各种名称，而只喜欢一个特定的名称):
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):
//
// 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'], $name);
}
这里的关键是xpath查询.使用两个，第一个用于获取具有某些标签的节点.我认为这对您来说是最有趣的:
The key point here are the xpath queries. Two are used, the first one to get the nodes that have certain tags. I think this is the most interesting one for you:
//node[tag[@k = "amenity" and @v = "school"]]
这行说:给我所有具有 tag 元素的所有 node 元素，元素中具有 k 属性值"amenity "和 v 属性值" school".这是您必须过滤掉带有便利学校标签的节点的条件.
This line says: Give me all node elements that have a tag element inside which has the k attribute value "amenity" and the v attribute value "school". This is the condition you have to filter out those nodes that are tagged with amenity school.
再次在xpath上再次使用，现在相对于那些学校节点，查看是否有名称，如果有的话，取其名称:
Further on xpath is used again, now relative to those school nodes to see if there is a name and if so to fetch it:
tag[@k = "name"]/@v'
此行说:相对于当前节点，从 tag 元素中给我一个 v 属性，该元素作为 k 属性值名称" .如您所见，某些部分再次与之前的代码相似.我认为你们俩都可以根据自己的需要采用它们.
This line says: Relative to the current node, give me the v attribute from a tag element that as the k attribute value "name". As you can see, some parts are again similar to the line before. I think you can both adopt them to your needs.
由于并非所有 school 节点都具有名称，因此通过将其添加到(然后为空)结果数组中来提供用于显示目的的默认字符串:
Because not all school nodes have a name, a default string is provided for display purposes by adding it to the (then empty) result array:
list($name) = $school->xpath('tag[@k = "name"]/@v') + ['(unnamed)'];
^^^^^^^^^^^^^^^
Provide Default Value
所以这是该代码示例的结果:
So here my results for that code-example:
Query returned 907 node(s) and took 1.10735 seconds.
10 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 [39.1347698,16.0736924] (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
我希望这已经有用，如果您还有其他澄清问题，请告诉我.
I hope this is useful already, let me know if you have more clarification questions.
(通过 rbwilkinson ):这是您可以添加其他参数以查找其他值的方法.下面的示例查找一公里范围内的其他属性:
(by rbwilkinson): This is how you could add additional parameters to find other values. the following example finds other properties within one kilometer:
$query = 'node
["addr:postcode"~"RM12"]
(51.5557914,0.2118915,51.5673083,0.2369398);
node
(around:1000)
["amenity"~"fast_food"];
out;';
$context = stream_context_create(['http' => [
'method' => 'POST',
'header' => ['Content-Type: application/x-www-form-urlencoded'],
'content' => 'data=' . urlencode($query),
]]);
$endpoint = 'http://overpass-api.de/api/interpreter';
libxml_set_streams_context($context);
$result = simplexml_load_file($endpoint);
printf("Query returned %2\$d node(s) and took %1\$.5f seconds.\n\n", microtime(true) - $start, count($result->node));
}
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