Question

对不起，我不太确定如何用言语表达我想要的东西。基本上我想得到一个密钥代码为0001的最小日期，我将如何实现呢？

$a=array(
  "a" => array('keycode' => '0001','date' =>"2015-09-08"),
  "b" => array('keycode' => '0002','date' =>"2015-09-05"),
  "c" => array('keycode' => '0003','date' =>"2015-09-04"),
  "d" => array('keycode' => '0001','date' =>"2015-09-01")
  "e" => array('keycode' => '0001','date' =>"2015-08-01")
);

预期：$ result =＆＃34; 2015-08-01＆＃34;

Answer 1

这将有效：

function min_date($a){
 $dates = [];
 foreach($a as $key => $value){
 if($value['keycode']=='0001'){
    array_push($dates,strtotime($value['date']));
  }
 }
 return date("Y/m/d",min($dates));
}

$result = min_date($a);

Answer 2

我首先会提取所有键码为0001的值，并创建一个仅包含这些日期的新数组。然后使用php min()函数。

PHP Fiddle

$a=array(
  "a" => array('keycode' => '0001','date' =>"2015-09-08"),
  "b" => array('keycode' => '0002','date' =>"2015-09-05"),
  "c" => array('keycode' => '0003','date' =>"2015-09-04"),
  "d" => array('keycode' => '0001','date' =>"2015-09-01"),
  "e" => array('keycode' => '0001','date' =>"2015-08-01")
);

$b = [];

foreach($a as $key => $value){
    if($value['keycode']=='0001'){
     $b[]=$value['date'];
    }
}

print_r($b);

echo min($b);

Answer 3

这样就可以了 -

$a=array(
  "a" => array('keycode' => '0001','date' =>"2015-09-08"),
  "b" => array('keycode' => '0002','date' =>"2015-09-05"),
  "c" => array('keycode' => '0003','date' =>"2015-09-04"),
  "d" => array('keycode' => '0001','date' =>"2015-09-01"),
  "e" => array('keycode' => '0001','date' =>"2015-08-01")
);

// Sort the array according to date in ascending order
usort($a, function($m, $n) {
     return strtotime($m['date']) - strtotime($n['date']);
});

// Take out the first element
$first= array_shift($a);

echo $first['date'];

Answer 4

您可以结合使用array_filter和uasort：

来执行此操作

function getMinDateByKeycode(array $a, $keycode)
{
    // Filter out elements by keycode
    $aFiltered = array_filter($a, function($aItem) use ($keycode) {
        return $aItem['keycode'] === $keycode;
    });

    // Sort lowest date first
    uasort($aFiltered, function($a1, $a2){
        return strtotime($a1['date']) - strtotime($a2['date']);
    });

    // Get the key of the first element of the resulting array
    reset($aFiltered);
    $keyOfMinDate = key($aFiltered);

    // Return it however you want. This example returns just the date.
    return $a[$keyOfMinDate]['date'];
}

echo getMinDateByKeycode($a, '0001');
// prints '2015-08-01'

Answer 5

如果数组已经排序并且你使用的是PHP 5.5.0+，那么你可以试试这个

$arr = array_column($a, "date", "keycode");
echo $arr["0001"] // string(10) "2015-08-01"

了解多维数组

5 个答案: