PHP array intersection judgment and optimization program code_PHP tutorial

Yesterday, I had a function that needed to judge the intersection of multiple generated arrays, that is, to judge whether there is an intersection in these arrays. Now I will introduce to you the PHP array intersection judgment program code example. Friends in need can refer to it. ​

It is necessary to determine whether two arrays intersect. The first thing I felt was that there should be this function in PHP. Sure enough:

array array_intersect(array array1,array array2[,arrayN…])

Returns the intersection elements in N arrays. If it is an associative array, you can use array_intersect_assoc()

PHP case is as follows:

Intersection of arrays array_intersect()
The array_intersect() function returns a key-preserved array consisting only of values ​​that appear in the first array and appear in every other input array. Its form is as follows:

The code is as follows

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代码如下	复制代码
$fruit1 = array("Apple","Banana","Orange"); $fruit2 = array("Pear","Apple","Grape"); $fruit3 = array("Watermelon","Orange","Apple"); $intersection = array_intersect($fruit1, $fruit2, $fruit3); print_r($intersection); // 输出 Array ( [0] => Apple ) ?>

$fruit1 = array("Apple","Banana","Orange");

$fruit2 = array("Pear","Apple","Grape");

代码如下	复制代码
if($user->role != 1){             $count = count($projects);             for($i=0;$i                 if(!array_intersect(explode(',', $projects[$i]['role']),  explode(',', $projects[$i]['next_approve_role']))){                     unset($projects[$i]);                     continue;                 }             }  }

$fruit3 = array("Watermelon","Orange","Apple");

$intersection = array_intersect($fruit1, $fruit2, $fruit3); print_r($intersection); // Output Array ( [0] => Apple )

?>

代码如下	复制代码
$fruit1 = array("red"=>"Apple","yellow"=>"Banana","orange"=>"Orange"); $fruit2 = array("yellow"=>"Pear","red"=>"Apple","purple"=>"Grape"); $fruit3 = array("green"=>"Watermelon","orange"=>"Orange","red"=>"Apple"); $intersection = array_intersect_assoc($fruit1, $fruit2, $fruit3); print_r($intersection); // output // Array ( [red] => Apple ) ?>

My application is as follows:

The code is as follows

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if($user->role != 1){                $count = count($projects); for($i=0;$i If(!array_intersect(explode(',', $projects[$i]['role']), explode(',', $projects[$i]['next_approve_role']))){                                                                                                                                                                                                                         unset($projects[$i]);                          continue;                 }             } }

Intersection of associative arrays array_intersect_assoc()

The code is as follows	Copy code
$fruit1 = array("red"=>"Apple","yellow"=>"Banana","orange"=>"Orange") ; $fruit2 = array("yellow"=>"Pear","red"=>"Apple","purple"=>"Grape"); $fruit3 = array("green"=>"Watermelon","orange"=>"Orange","red"=>"Apple"); $intersection = array_intersect_assoc($fruit1, $fruit2, $fruit3); print_r($intersection); //output // Array ( [red] => Apple ) ?>

Optimization of array intersection

Assume that each parameter will contain about a thousand product IDs (int), and use this as a premise to simulate and generate some data:

The code is as follows

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代码如下	复制代码
$rand = function() {     $result = array();     for ($i = 0; $i         $result[] = mt_rand(1, 10000);     }     return $result; }; $param_a = $rand(); $param_b = $rand(); ?>

$rand = function() {
$result = array();

for ($i = 0; $i          $result[] = mt_rand(1, 10000);
}

代码如下	复制代码
$time = microtime(true); $result = array_intersect($param_a, $param_b); $time = microtime(true) - $time; echo "array_intersect: {$time}n"; ?>

return $result;
};

代码如下	复制代码
$param_a = array(1, 2, 2); $param_b = array(1, 2, 3); var_dump(     array_intersect($param_a, $param_b),     array_intersect($param_b, $param_a) ); ?>

$param_a = $rand();
$param_b = $rand(); ?>

Note: If the test data set is too small, the conclusions may be inconsistent. Let’s first look at the performance achieved through PHP’s built-in method array_intersect:

The code is as follows	Copy code
$time = microtime(true); $result = array_intersect($param_a, $param_b); $time = microtime(true) - $time; echo "array_intersect: {$time}n"; ?>

Before optimizing, let’s take a look at some special features of array_intersect:

The code is as follows	Copy code
$param_a = array(1, 2, 2); $param_b = array(1, 2, 3); var_dump( Array_intersect($param_a, $param_b), Array_intersect($param_b, $param_a) ); ?>

array_intersect($param_a, $param_b): 1, 2, 2
array_intersect($param_b, $param_a): 1, 2
That is to say, if there are duplicate elements in the first array parameter, array_intersect will return all duplicate elements that meet the conditions. It is best to be compatible with these functions when rewriting array_intersect.

Let’s take a look at the performance achieved through the custom method int_array_intersect:

The code is as follows

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代码如下

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function int_array_intersect() {     if (func_num_args()         trigger_error('param error', E_USER_ERROR);     }     $args = func_get_args();     foreach ($args AS $arg) {         if (!is_array($arg)) {             trigger_error('param error', E_USER_ERROR);         }     }     $intersect = function($a, $b) {         $result = array();         $length_a = count($a);         $length_b = count($b);         for ($i = 0, $j = 0; $i             if($a[$i]                 continue;             }             if($a[$i] > $b[$j] && ++$j) {                 continue;             }             $result[] = $a[$i];             if (isset($a[$next = $i + 1]) && $a[$next] != $a[$i]) {                 ++$j;             }             ++$i;         }         return $result;     };     $result = array_shift($args);     sort($result);     foreach ($args as $arg) {         sort($arg);         $result = $intersect($result, $arg);     }     return $result; } $time = microtime(true); $result = int_array_intersect($param_a, $param_b); $time = microtime(true) - $time; echo "int_array_intersect: {$time}n"; ?>

function int_array_intersect()

{
If (func_num_args()         trigger_error('param error', E_USER_ERROR);
}

$args = func_get_args();

foreach ($args AS $arg) { If (!is_array($arg)) {              trigger_error('param error', E_USER_ERROR); } } $intersect = function($a, $b) {           $result = array(); $length_a = count($a);          $length_b = count($b);

for ($i = 0, $j = 0; $i If($a[$i]                          continue;

            }

if($a[$i] > $b[$j] && ++$j) {                        continue;             } $result[] = $a[$i]; if (isset($a[$next = $i + 1]) && $a[$next] != $a[$i]) {               ++$j;             }           ++$i; } return $result; }; $result = array_shift($args); Sort($result); foreach ($args as $arg) {         sort($arg);          $result = $intersect($result, $arg); } return $result; } $time = microtime(true); $result = int_array_intersect($param_a, $param_b); $time = microtime(true) - $time; echo "int_array_intersect: {$time}n"; ?>

Intuitively, we would think that built-in functions are faster than custom functions, but in this case the opposite is true: array_intersect: 0.023918151855469 int_array_intersect: 0.0026049613952637 http://www.bkjia.com/PHPjc/445278.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/445278.htmlTechArticleYesterday I had a function that needed to determine the intersection of multiple generated arrays, that is, to determine whether there is an intersection in these arrays There is an intersection. Now let me introduce to you the process of judging the intersection of PHP arrays...