PHP-从元素组检索最低和最高值 [英] PHP - retrieve lowest and highest values from elements groups

问题描述

找不到正确的方法来执行以下操作:我有xml，其中包含每个元素都有一个属性顺序且值的范围为0-3的元素.它们由该属性(0,1,2,3,0,1,2,3 ...)进行排序，并且是同级.许多元素可以变化，并且文档中的第一个元素不必以0开头，因为XML每4小时刷新一次，并且每次刷新时，当前的第一个元素都将被删除，而行中的下一个元素则位于第一个位置.例如:上午0:00，第一个元素的属性为order ="0".在6:00，它被删除，下一个兄弟姐妹以属性order ="1"的身份成为他(第一个)位置.

Can't find a proper way to do the following: i have xml which contains elements where each one has a attribute order and the value ranging from 0-3. They are ordered by that attribute (0,1,2,3,0,1,2,3...) and are siblings. A number of the elements can vary and it's not necessary that the first one in the document starts with 0 as the XML is refreshed every 4 hours and with every refresh the current first element get's deleted and the next element in line take's over the first position. For example: at 0:00 am the first element has attribute order="0". At 6:00 it gets removed and the next sibling takes he's (first) place with attribute order="1".

我想对一组元素按从0到3的顺序进行循环(第一个元素除外，第一个元素的顺序可能为0、1、2或3)，并检索最低和最高值每个组子节点的数量.例如:

I would like to do a loop for a group of elements where they are ordered from 0-3 (except the first group where the first element may have order 0, 1, 2, or 3) and retrieve lowest and highest values of each group child nodes. For example:

Lopping the bottom structure should print:

11, 82
2, 92
1, 211
...

<parent>

    <!-- Group 1 -->
    <element order="2">
        <node value="30" />
        <node value="82" /> <!-- This is the highest of the Group 1 -->
        <node value="25" />
    </element>
    <element order="3">
        <node value="12" />
        <node value="52" />
        <node value="11" /> <!-- This is the lowest of the Group 1 -->
    </element>

    <!-- Group 2 -->
    <element order="0">
        <node value="21" />
        <node value="78" />
        <node value="33" />
    </element>
    <element order="1">
        <node value="35" />
        <node value="57" />
        <node value="88" />
    </element>
    <element order="2">
        <node value="22" />
        <node value="92" /> <!-- This is the highest of the Group 2 -->
        <node value="81" /> 
        <node value="19" />
    </element>
    <element order="3">
        <node value="2" /> <!-- This is the lowest of the Group 2 -->
        <node value="30" />
        <node value="44" />
    </element>

    <!-- Group 3 -->
    <element order="0">
        <node value="12" />
        <node value="99" />
        <node value="43" />
    </element>
    <element order="1">
        <node value="65" />
        <node value="211" /> <!-- This is the highest of the Group 3 -->
        <node value="16" />
    </element>
    <element order="2">
        <node value="32" />
        <node value="55" />
        <node value="77" /> 
        <node value="1" /> <!-- This is the lowest of the Group 3 -->
    </element>
    <element order="3">
        <node value="68" />
        <node value="74" />
        <node value="21" />
    </element>
    <!-- Group 4 -->
    ...

</parent>

希望这个问题不会被广泛问到.注释不包含在XML中.

Hope the question is not to widely asked. The comments are not included in the XML.

推荐答案

这是一种方法.

仅当属性按顺序排列时，此解决方案才有效1, 3, 4，而不是3, 0, 4.

This solution will only work if the attributes are ordered e.g. 1, 3, 4 and not e.g. 3, 0, 4.

$string = <<<XML
<!-- XML data goes here -->
XML;

// suppress some errors
libxml_use_internal_errors(true);

$xml = simplexml_load_string($string);

// step 1: group all the values

// keep track of the previous order to determine when we have a new group
// INF is just an arbitrarily large number to start the first group
$prevOrder = INF; 
$groups = [];
$i = -1;

foreach ($xml->element as $element) {
    $order = (int) $element->attributes()['order'];
    // start a new group if the current order is smaller than the previous order
    if ($order <= $prevOrder) {
        $groups[++$i] = [];
    }
    // store the next values in that group
    foreach ($element->node as $node) {
        $groups[$i][] = (int) $node->attributes()['value'];
    }
    $prevOrder = $order;
}

// step 2: get the minimum and maximum of each group

foreach ($groups as $group) {
    printf('%d, %d<br>', min($group), max($group));
}

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