PHP入れ子配列からキー値を抽出する

Question

次の配列を返すAPI呼び出しがあります。私がPHPでやろうとしているのは、[by_category]配列内のオブジェクトのみのキー値を取得することです。私はその配列のビューのカテゴリ名と値だけを表示したい。しかし、これらのネストされた配列をどのようにループして、それらの値だけを取得し、[by_date]配列内のすべてを無視するかについては固執しています。どこから始めるべき？どのようなサンプルコードを私はバイブルすることができますか？

Array 
(
    [by_date] => Array 
    (
     [0] => Array 
      (
       [id] => 
       [date] => 2016-11-10 
       [views] => 1202 
       [participations] => 29 
      ) 

     [1] => Array 
      (
       [id] => 
       [date] => 2016-09-10 
       [views] => 2068 
       [participations] => 66 
      ) 

     [2] => Array 
      (
       [id] => 
       [date] => 2016-11-14 
       [views] => 1760 
       [participations] => 41 
      ) 

     [3] => Array 
      (
       [id] => 
       [date] => 2017-01-01 
       [views] => 122 
       [participations] => 3 
      ) 

     [4] => Array 
      (
       [id] => 
       [date] => 2016-10-06 
       [views] => 2113 
       [participations] => 102 
      ) 

     [5] => Array 
      (
       [id] => 
       [date] => 2016-08-31 
       [views] => 1986 
       [participations] => 110 
      ) 

     [6] => Array 
      (
       [id] => 
       [date] => 2016-07-26 
       [views] => 127 
       [participations] => 3 
      ) 

     [7] => Array 
      (
       [id] => 
       [date] => 2016-12-03 
       [views] => 826 
       [participations] => 24 
      ) 

     [8] => Array 
      (
       [id] => 
       [date] => 2016-11-13 
       [views] => 796 
       [participations] => 20 
      ) 

    ) 

[by_category] => Array 
    (
     [0] => Array 
      (
       [id] => 
       [category] => announcements 
       [views] => 2639 
      ) 

     [1] => Array 
      (
       [id] => 
       [category] => assignments 
       [views] => 21611 
      ) 

     [2] => Array 
      (
       [id] => 
       [category] => collaborations 
       [views] => 6 
      ) 

     [3] => Array 
      (
       [id] => 
       [category] => conferences 
       [views] => 6 
      ) 

     [4] => Array 
      (
       [id] => 
       [category] => discussions 
       [views] => 29962 
      ) 

     [5] => Array 
      (
       [id] => 
       [category] => files 
       [views] => 13649 
      ) 

     [6] => Array 
      (
       [id] => 
       [category] => general 
       [views] => 23497 
      ) 

     [7] => Array 
      (
       [id] => 
       [category] => grades 
       [views] => 5473 
      ) 

     [8] => Array 
      (
       [id] => 
       [category] => groups 
       [views] => 231 
      ) 

     [9] => Array 
      (
       [id] => 
       [category] => modules 
       [views] => 27258 
      ) 

     [10] => Array 
      (
       [id] => 
       [category] => other 
       [views] => 18186 
      ) 

     [11] => Array 
      (
       [id] => 
       [category] => pages 
       [views] => 16576 
      ) 

     [12] => Array 
      (
       [id] => 
       [category] => quizzes 
       [views] => 6206 
      ) 

    ) 

) 

Answer 1

そのforeachのが簡単に：

foreach($array['by_category'] as $category){ 
    echo 'id='. $category['id'] . ' , name='.$category['category']; 
}