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PHP获取二维数组中某一列的值集合_PHP

May 28, 2016 am 11:49 AM

PHP还是比较常用的,于是我研究了一下PHP二维数组。在处理php数组的时候,有一种需求特别的频繁,如下二维数组:

$arr = array(
1=>array(
'id' => 5,
'name' => '张三'
),
2=>array(
'id' => 6,
'name' => '李四'
)
);
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目的就是要取到key为name的集合,得到这个结果:

$arr2 = array(
0=>'张三',
1=>'李四'
);
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这里有几种方法:

1:最简单的,foreach遍历数组:

foreach ($arr as $key => $value) {
$arr2[] = $value['name'];
}
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2:代码量稍微少一点的代码,使用了 array_map 这个php方法:

$arr2 = array_map('array_shift',$arr);
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意为把$arr数组的每一项值的开头的值移出,并返回被移出的每一项值中被移出的值,注意此时新数组$arr2的键仍是原数组$arr的键

2.1:在方法2的基础上,可以稍微开一下脑洞,如果需要获取的是二维数组的每一项的开头列或结尾列,也可以这样做:

$arr2 = array_map('reset',$arr);
$arr2 = array_map('end',$arr);
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哈哈,也是很方便的

3:还可以使用 array_reduc e方法,不过代码略多,不过这个方法的想象空间(针对别的数组取值操作)还是蛮大的:

$arr2 = array_reduce($arr, create_function('$result, $v', '$result[] = $v["name"];return $result;'));
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array_reduce方法用回调函数迭代地将对数组的值进行操作,而create_function用于一个匿名方法做回调用,这个匿名方法的参数$result为上一次迭代产生的值,$v是当前的值,内部实现既为获取到数组$arr每一项的”name”的值并push到新$result数组;

4:最后这个终极方法实在是太爽了,一个方法就搞定,而且非常灵活:

$arr2 = array_column($arr, 'name');
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第二个参数为想要获取的那一列的键名,是不是很方便呢,不过这个方法有个限制,就是php版本必须 >= 5.5.0,在陈旧项目中使用这个方法还是得斟酌一下哈

PS: php中遍历二维数组的几种方式

<&#63;php
//使用for循环遍历
$arr2=array(array("张三","20","男"),array("李四","25","男"),array("王五","19","女"),array("赵六","25","女"));
echo "<table border=2 bordercolor=red><tr><td>姓名</td><td>年龄</td& gt;<td>性别</td></tr>";
for($i=0;$i<4;$i++){
echo "<tr>";
for($j=0;$j<3;$j++){
  echo "<td>";
  echo $arr2[$i][$j];
  echo "</td>";
}
echo "</tr>";
echo "<br>";
}
echo "</table>";
&#63;>
//使用foreach遍历
<&#63;php
$arr = array('one'=>array('name'=>'张三','age'=>'23','sex'=>'男'),
  'two'=>array('name'=>'李四','age'=>'43','sex'=>'女'),
  'three'=>array('name'=>'王五','age'=>'32','sex'=>'男'),
  'four'=>array('name'=>'赵六','age'=>'12','sex'=>'女'));
foreach($arr as $k=>$val){
  echo $val['name'].$val['age'].$val['sex']."<br>";
}
echo "<p>";
&#63;>
<&#63;php
$arr = array('one'=>array('name'=>'张三','age'=>'23','sex'=>'男'),
  'two'=>array('name'=>'李四','age'=>'43','sex'=>'女'),
  'three'=>array('name'=>'王五','age'=>'32','sex'=>'男'),
  'four'=>array('name'=>'赵六','age'=>'12','sex'=>'女'));
foreach($arr as $key=>$value){
foreach($value as $key2=>$value2){
  echo $value2;
}
echo "<br>";
}
&#63;>
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