PHP循环返回一个额外的不需要的数组(Wikipedia API)

Question

我一整天都在研究这个问题，还没有找到任何解决办法。我对php也很陌生。

我的函数的目的是获取维基百科文章的用户输入(Category1)并返回其类别。下面的基本功能可以做到这一点，没有任何问题。

function get_all_categories ( ) {

        $url = $this->get_url ( 'categories' ) ;
        $url .= 'titles='.urlencode($_POST['Category1']);
        $url .= '&cllimit=500' ;        
        $data = $this->get_result ( $url ) ;

        $array = json_decode($data, true); }

城市规划实例结果

Array
(
[batchcomplete] => 
[query] => Array
    (
        [pages] => Array
            (
                [46212943] => Array
                    (
                        [pageid] => 46212943
                        [ns] => 0
                        [title] => Urban planning
                        [categories] => Array
                            (
                                [0] => Array
                                    (
                                        [ns] => 14
                                        [title] => Category:All Wikipedia articles written in American English
                                    )

                                [1] => Array
                                    (
                                        [ns] => 14
                                        [title] => Category:Commons category with local link same as on Wikidata
                                    )

                                [2] => Array
                                    (
                                        [ns] => 14
                                        [title] => Category:Pages using ISBN magic links
                                    )

                                [3] => Array
                                    (
                                        [ns] => 14
                                        [title] => Category:Urban planning
                                    )

                                [4] => Array
                                    (
                                        [ns] => 14
                                        [title] => Category:Use American English from April 2015
                                    )

                                [5] => Array
                                    (
                                        [ns] => 14
                                        [title] => Category:Use dmy dates from April 2015
                                    )

                                [6] => Array
                                    (
                                        [ns] => 14
                                        [title] => Category:Wikipedia articles needing clarification from June 2015
                                    )

                                [7] => Array
                                    (
                                        [ns] => 14
                                        [title] => Category:Wikipedia articles with GND identifiers
                                    )

                            )

                    )

            )

    )

)

当我试图从这个数组中只提取标题值时，我的问题就开始了。我尝试用foreach循环来实现这一点，这是我为多维数组找到的最简单的解决方案：

$array1 = new RecursiveIteratorIterator(
        new RecursiveArrayIterator($array),
        RecursiveIteratorIterator::SELF_FIRST);

        foreach ($array1 as $key => $value) {
            if (is_array($value) && $key == 'categories') {
                $result = array_map(function($element){return $element['title'];}, $value);

                print_r($result);
                }               
        }

我从这段代码中得到的是两个数组。一个数组只有标题(我想要的)，但也有一个不想要的数组(有时包括第一个标题)附加在末尾：

Array
(
[0] => Category:All Wikipedia articles written in American English
[1] => Category:Commons category with local link same as on Wikidata
[2] => Category:Pages using ISBN magic links
[3] => Category:Urban planning
[4] => Category:Use American English from April 2015
[5] => Category:Use dmy dates from April 2015
[6] => Category:Wikipedia articles needing clarification from June 2015
[7] => Category:Wikipedia articles with GND identifiers
)
Array
(
[ns] => 
[title] => C
)

这个额外的数组是我不明白的。我认为这个问题是由前缘循环引起的。我尝试在循环之外取消设置$variable，但没有帮助。如果我试图将这些结果传递给另一个函数，那么额外的数组就会变得特别麻烦。我怎样才能防止这种情况发生呢？

Answer 1

为了简单起见，您可以手动遍历数组，而不是使用RecursiveIteratorIterator。

RecursiveIteratorIterator将用于大型数组的杀灭性能。

将提取逻辑更改为：

$result = array();
foreach($arr['batchcomplete']['query']['pages'] as $k => $v)
{
    foreach($v['categories'] as $cat)
    {
        $result[] = $cat['title'];
    }
}

https://eval.in/709842

Answer 2

正如@samir所提到的，手动执行会更快，但是如果需要遍历未知深度的搜索机制，也可以使用基本的递归函数。它可能比OOP风格的RecursiveArrayIterator/RecursiveIteratorIterator:快一点。

function recurse($array,&$new)
    {
        foreach($array as $key => $value) {
            if($key == 'title' && isset($array['ns'])) {
                if(!isset($array['pageid']))
                    $new[]  =   $value;
            }
            else {
                if(is_array($value)) {
                    recurse($value,$new);
                }
            }
        }
    }

# Set's storage array for final titles
$new    =   array();
# Recurse your array
recurse($array,$new);
# Show stored values
print_r($new);