根据字符串值对数组项目进行分组

Question

我想按sport对数组进行分组。它可能是n体育的数量。最后，用它创建一个新的数组。有没有一种有效的方法，而不会矫枉过正？

$sports = [ 
    ['sport' => 'soccer', 'id' => 97487]; 
    ['sport' => 'soccer', 'id' => 244800]; 
    ['sport' => 'soccer', 'id' => 258740]; 
    ['sport' => 'basketball', 'id' => 147884]; 
    ['sport' => 'baseball', 'id' => 222240]; 
    ['sport' => 'baseball', 'id' => 222245]; 
]; 

初始阵列：

array(6) { 
    [0]=> 
    array(2) { 
    ["sport"]=> 
    string(6) "soccer" 
    ["id"]=> 
    int(97487) 
    } 
    [1]=> 
    array(2) { 
    ["sport"]=> 
    string(6) "soccer" 
    ["id"]=> 
    int(244800) 
    } 
    [2]=> 
    array(2) { 
    ["sport"]=> 
    string(6) "soccer" 
    ["id"]=> 
    int(258740) 
    } 
    [3]=> 
    array(2) { 
    ["sport"]=> 
    string(10) "basketball" 
    ["id"]=> 
    int(147884) 
    } 
    [4]=> 
    array(2) { 
    ["sport"]=> 
    string(8) "baseball" 
    ["id"]=> 
    int(222240) 
    } 
    [5]=> 
    array(2) { 
    ["sport"]=> 
    string(8) "baseball" 
    ["id"]=> 
    int(222245) 
    } 
} 

期望的结果：

array(3) 
{ 
    [0]=> 
    array(3) { 
     [0]=> 
     array(2) { 
      ["sport"]=> 
      string(6) "soccer" 
      ["id"]=> 
      int(97487) 
     } 
     [1]=> 
     array(2) { 
      ["sport"]=> 
      string(6) "soccer" 
      ["id"]=> 
      int(244800) 
     } 
     [2]=> 
     array(2) { 
      ["sport"]=> 
      string(6) "soccer" 
      ["id"]=> 
      int(258740) 
     } 
    } 
    [1]=> 
     array(1) { 
     [0]=> 
     array(2) { 
      ["sport"]=> 
      string(10) "basketball" 
      ["id"]=> 
      int(147884) 
     } 
    } 
    [2]=> 
    array(2) { 
     [0]=> 
     array(2) { 
      ["sport"]=> 
      string(8) "baseball" 
      ["id"]=> 
      int(222240) 
     } 
     [1]=> 
     array(2) { 
      ["sport"]=> 
      string(8) "baseball" 
      ["id"]=> 
      int(222245) 
     } 
    } 
} 

Answer 1

您可以将像这样的数组：

$sports = [ 
    ['sport' => 'soccer', 'id' => 97487], 
    ['sport' => 'soccer', 'id' => 244800], 
    ['sport' => 'soccer', 'id' => 258740], 
    ['sport' => 'basketball', 'id' => 147884], 
    ['sport' => 'baseball', 'id' => 222240], 
    ['sport' => 'baseball', 'id' => 222245] 
]; 

// we will build an array here where the key is the sport 
// name and the value is an array of objects pertaining 
// to that sport i.e. 'basketball' => [bb1, bb2, ...] 

$array = array(); 

// now consider every sport object in your original array 

foreach($sports as $key => $item) 
{ 
    if (array_key_exists($item['sport'], $array)) { 
    // we encountered this same sport in the past so we 
    // know $array['sportName'] already exists and can 
    // push right to it 
    $array[$item['sport']][] = $item; 
    } else { 
    // we have never seen this sport before and now must 
    // insert the sport into $array['sportName'] = [] 
    // and push this sport object to it 
    $array[$item['sport']] = [$item]; 
    } 
} 

// since $array's keys are the names of the sports themselves, but 
// you want the keys to be numeric, this will build a new array 
// from just the values of $array which at this point contains 
// grouped arrays of sport objects 

$result = array_values($array); 

// print the results for good measure :) 

print_r($result); 

这是通过循环您的体育阵列并建立第二批[sportName => arrayOfThatSport]。在for循环中，我们检查一下给定的运动是否已经存在于这个数组中。如果确实如此，那么将该运动添加到该运动的相应阵列中。否则，请在$array['sportName'] = [sportObject]处为该运动创建一个新阵列。如果您考虑循环的几次迭代，您会看到我们总是添加到现有的$array['sportName']阵列中，或者在遇到我们以前从未见过的新运动时在此位置创建新阵列。这给了我们最后一个数组，类似于：[ "sport : [...], "sport2": [...] ]但在你的情况下，你想要一个数组而不是关联数组，因此调用array_values。

Answer 2

这是我建议的解决方案。

$groupedSports = []; 
foreach ($sports as $item) { 
    if (empty($groupedSports[$item['sport']])) { 
     $groupedSports[$item['sport']] = []; 
    } 
    $groupedSports[$item['sport']][] = $item; 
} 

简短说明：

• 线1：我们初始化一个空数组
• 线2：我们开始最初的阵列上的循环
• 线3-5：如果它是第一个对于当前运动，我们初始化一个空阵列（避免警告）
• 第6行：我们将当前项分配给相应的阵列