PHP array_filter（）関数を介して配列内の特定の要素を柔軟にフィルタリングする方法は？

M66 2025-07-29
<span><span><span class="hljs-meta">&lt;?php</span></span><span>
</span><span><span class="hljs-comment">// -------------------------------------------------------------</span></span><span>

</span><span><span class="hljs-comment">// PHP array_filter() 関数の紹介と柔軟なフィルタリングアプリケーション</span></span><span>

</span><span><span class="hljs-comment">// -------------------------------------------------------------</span></span><span>

<span class="hljs-comment">/**
 * 存在する PHP 真ん中，array_filter() これは非常に強力な組み込み機能です，
 * 它能够通过回调函数对数组真ん中要素进行筛选，
 * 基準を満たすサブアレイを返します，これにより、開発者はデータを柔軟に処理できます。
 * この記事では詳細に紹介します array_filter() 使用法といくつかの実用的なスクリーニング技術。
 */</span>

</span><span><span class="hljs-comment">// 1. 基本的な使用法：空でない要素を除外します</span></span><span>
</span><span><span class="hljs-variable">$input</span></span><span> = [</span><span><span class="hljs-number">0</span></span><span>, </span><span><span class="hljs-number">1</span></span><span>, </span><span><span class="hljs-number">2</span></span><span>, </span><span><span class="hljs-string">''</span></span><span>, </span><span><span class="hljs-literal">null</span></span><span>, </span><span><span class="hljs-literal">false</span></span><span>, </span><span><span class="hljs-string">'hello'</span></span><span>, </span><span><span class="hljs-string">'0'</span></span><span>];
</span><span><span class="hljs-variable">$filtered</span></span><span> = </span><span><span class="hljs-title function_ invoke__">array_filter</span></span><span>(</span><span><span class="hljs-variable">$input</span></span><span>);
</span><span><span class="hljs-title function_ invoke__">print_r</span></span><span>(</span><span><span class="hljs-variable">$filtered</span></span><span>);
<span class="hljs-comment">/*
結果：
Array
(
    [1] =&gt; 1
    [2] =&gt; 2
    [6] =&gt; hello
)
*/</span>
</span><span><span class="hljs-comment">// 説明します：コールバック関数が提供されていない場合，array_filter() デフォルトですべてを削除します“に相当 false”の値。</span></span><span>

</span><span><span class="hljs-comment">// 2. 特定の条件の要素をフィルタリングするカスタムコールバック関数</span></span><span>
</span><span><span class="hljs-variable">$numbers</span></span><span> = [</span><span><span class="hljs-number">1</span></span><span>, </span><span><span class="hljs-number">2</span></span><span>, </span><span><span class="hljs-number">3</span></span><span>, </span><span><span class="hljs-number">4</span></span><span>, </span><span><span class="hljs-number">5</span></span><span>, </span><span><span class="hljs-number">6</span></span><span>];
</span><span><span class="hljs-variable">$evenNumbers</span></span><span> = </span><span><span class="hljs-title function_ invoke__">array_filter</span></span><span>(</span><span><span class="hljs-variable">$numbers</span></span><span>, function(</span><span><span class="hljs-variable">$num</span></span><span>) {
    </span><span><span class="hljs-keyword">return</span></span><span> </span><span><span class="hljs-variable">$num</span></span><span> % </span><span><span class="hljs-number">2</span></span><span> === </span><span><span class="hljs-number">0</span></span><span>;
});
</span><span><span class="hljs-title function_ invoke__">print_r</span></span><span>(</span><span><span class="hljs-variable">$evenNumbers</span></span><span>);
<span class="hljs-comment">/*
結果：
Array
(
    [1] =&gt; 2
    [3] =&gt; 4
    [5] =&gt; 6
)
*/</span>
</span><span><span class="hljs-comment">// 説明します：コールバック関数が返されます true の要素，false ろ過されます。</span></span><span>

</span><span><span class="hljs-comment">// 3. キー名フィルタリングを使用します</span></span><span>
</span><span><span class="hljs-variable">$assoc</span></span><span> = [
    </span><span><span class="hljs-string">'apple'</span></span><span> =&gt; </span><span><span class="hljs-number">3</span></span><span>,
    </span><span><span class="hljs-string">'banana'</span></span><span> =&gt; </span><span><span class="hljs-number">5</span></span><span>,
    </span><span><span class="hljs-string">'cherry'</span></span><span> =&gt; </span><span><span class="hljs-number">1</span></span><span>,
    </span><span><span class="hljs-string">'date'</span></span><span> =&gt; </span><span><span class="hljs-number">7</span></span><span>,
];
</span><span><span class="hljs-comment">// キー名の長さのみがより大きくなります5要素</span></span><span>
</span><span><span class="hljs-variable">$filteredByKey</span></span><span> = </span><span><span class="hljs-title function_ invoke__">array_filter</span></span><span>(</span><span><span class="hljs-variable">$assoc</span></span><span>, function(</span><span><span class="hljs-variable">$value</span></span><span>, </span><span><span class="hljs-variable">$key</span></span><span>) {
    </span><span><span class="hljs-keyword">return</span></span><span> </span><span><span class="hljs-title function_ invoke__">strlen</span></span><span>(</span><span><span class="hljs-variable">$key</span></span><span>) &gt; </span><span><span class="hljs-number">5</span></span><span>;
}, ARRAY_FILTER_USE_BOTH);
</span><span><span class="hljs-title function_ invoke__">print_r</span></span><span>(</span><span><span class="hljs-variable">$filteredByKey</span></span><span>);
<span class="hljs-comment">/*
結果：
Array
(
    [banana] =&gt; 5
    [cherry] =&gt; 1
)
*/</span>

</span><span><span class="hljs-comment">// 4. マルチレイヤーアレイフィルターの例</span></span><span>
</span><span><span class="hljs-variable">$users</span></span><span> = [
    [</span><span><span class="hljs-string">'name'</span></span><span> =&gt; </span><span><span class="hljs-string">'Alice'</span></span><span>, </span><span><span class="hljs-string">'age'</span></span><span> =&gt; </span><span><span class="hljs-number">23</span></span><span>, </span><span><span class="hljs-string">'active'</span></span><span> =&gt; </span><span><span class="hljs-literal">true</span></span><span>],
    [</span><span><span class="hljs-string">'name'</span></span><span> =&gt; </span><span><span class="hljs-string">'Bob'</span></span><span>, </span><span><span class="hljs-string">'age'</span></span><span> =&gt; </span><span><span class="hljs-number">30</span></span><span>, </span><span><span class="hljs-string">'active'</span></span><span> =&gt; </span><span><span class="hljs-literal">false</span></span><span>],
    [</span><span><span class="hljs-string">'name'</span></span><span> =&gt; </span><span><span class="hljs-string">'Charlie'</span></span><span>, </span><span><span class="hljs-string">'age'</span></span><span> =&gt; </span><span><span class="hljs-number">27</span></span><span>, </span><span><span class="hljs-string">'active'</span></span><span> =&gt; </span><span><span class="hljs-literal">true</span></span><span>],
];
</span><span><span class="hljs-comment">// より古い除外25アクティブユーザー</span></span><span>
</span><span><span class="hljs-variable">$activeAdults</span></span><span> = </span><span><span class="hljs-title function_ invoke__">array_filter</span></span><span>(</span><span><span class="hljs-variable">$users</span></span><span>, function(</span><span><span class="hljs-variable">$user</span></span><span>) {
    </span><span><span class="hljs-keyword">return</span></span><span> </span><span><span class="hljs-variable">$user</span></span><span>[</span><span><span class="hljs-string">'age'</span></span><span>] &gt; </span><span><span class="hljs-number">25</span></span><span> &amp;&amp; </span><span><span class="hljs-variable">$user</span></span><span>[</span><span><span class="hljs-string">'active'</span></span><span>] === </span><span><span class="hljs-literal">true</span></span><span>;
});
</span><span><span class="hljs-title function_ invoke__">print_r</span></span><span>(</span><span><span class="hljs-variable">$activeAdults</span></span><span>);
<span class="hljs-comment">/*
結果：
Array
(
    [2] =&gt; Array
        (
            [name] =&gt; Charlie
            [age] =&gt; 27
            [active] =&gt; 1
        )
)
*/</span>

</span><span><span class="hljs-comment">// 5. 予防策とパフォーマンスの提案</span></span><span>
</span><span><span class="hljs-comment">// - array_filter 配列は再セックスされません，元のキー名を保持します。</span></span><span>
</span><span><span class="hljs-comment">// - 継続的なインデックスが必要な場合，協力できます array_values 使用。</span></span><span>
</span><span><span class="hljs-comment">// - 存在する处理大数组时，コールバック関数ロジックを可能な限り簡素化します，パフォーマンスのボトルネックを避けてください。</span></span><span>

</span><span><span class="hljs-comment">// 要約します：</span></span><span>
</span><span><span class="hljs-comment">// array_filter() はい PHP 真ん配列要素をフィルタリングするための武器，コールバック関数の柔軟な定義，</span></span><span>
</span><span><span class="hljs-comment">// さまざまな複雑なスクリーニング要件を実現できます，コードのシンプルさと読みやすさを改善します。</span></span><span>

</span><span><span class="hljs-meta">?&gt;</span></span><span>
</span></span>
関連タグ:
array_filter
array