php 计算多维数组中的值
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Counting Values in Multidimensional Array
提问by lethalMango
I currently have the following array:
我目前有以下数组：
Array(
[0] => Array
(
[user] => Name 1
[group] => 1
)
[1] => Array
(
[user] => Name 2
[group] => 1
)
[2] => Array
(
[user] => Name 3
[group] => 2
)
[3] => Array
(
[user] => Name 4
[group] => 2
)
[4] => Array
(
[user] => Name 5
[group] => 3
)
)
I am attempting to create a new array with the various groupvalues as the key, then count how many are in each group to give the following:
我正在尝试创建一个以各种group值为键的新数组，然后计算每个组中有多少个以给出以下内容：
Array
(
[1] => 2
[2] => 2
[3] => 1
)
I have attempted to use the following, however I get undefined index warnings:
我尝试使用以下内容，但是我收到未定义的索引警告：
$newArr = array();
foreach ($details['user_groups'] as $key => $value) {
$newArr[$value['user_groups']]++;
}
(I did check SO for other answers, however couldn't find one attempting to do the same)
（我确实检查了其他答案，但是找不到试图做同样的事情）
回答by Michael Berkowski
This can be done with a simple iteration:
这可以通过一个简单的迭代来完成：
$counts = array();
foreach ($array as $key=>$subarr) {
// Add to the current group count if it exists
if (isset($counts[$subarr['group']]) {
$counts[$subarr['group']]++;
}
// or initialize to 1 if it doesn't exist
else $counts[$subarr['group']] = 1;
// Or the ternary one-liner version
// instead of the preceding if/else block
$counts[$subarr['group']] = isset($counts[$subarr['group']]) ? $counts[$subarr['group']]++ : 1;
}
Update for PHP 5.5
PHP 5.5 更新
In PHP 5.5, which has added the array_column()function to aggregate an inner key from a 2D array, this can be simplified to:
在 PHP 5.5 中，它添加了array_column()从 2D 数组聚合内部键的函数，这可以简化为：
$counts = array_count_values(array_flip(array_column($array, 'group')));
回答by Vijaysinh Parmar
This can be done with a simple array_mapfunction
这可以通过一个简单的array_map函数来完成
$array = array_map(function($element){
return $element['group'];
}, $array1);
$array2 = (array_count_values($array));
print_r($array2);
回答by FtDRbwLXw6
Your initial attempt was close. You were simply using the wrong key inside the loop:
您最初的尝试已接近尾声。您只是在循环中使用了错误的键：
$newArr = array();
foreach ($details['user_groups'] as $key => $value) {
// What you were using:
// $newArr[$value['user_groups']]++;
// What you should be using:
$newArr[$value['group']]++;
}
回答by nimtek123
Try this simple but effective way
试试这个简单但有效的方法
$count = call_user_func_array('array_merge_recursive', $Array);
echo count($count['user']).'<br>';
echo count($count['group']).'<br>';
回答by tiya Ra
$output = array();
foreach($data as $key => $value){
$output[$value['group']]['count']++;
}
$final = array();
foreach($output as $key => $value){
$final[$key] = $value['count'];
}
print_r($final);
//out put result:=========
Array(
[1] => 2
[2] => 2
[3] => 1
)
