array_count_values

(PHP 4, PHP 5, PHP 7)

array_count_values — 统计数组中所有的值

说明

array array_count_values ( array $array )

array_count_values() 返回一个数组： 数组的键是 array 里单元的值； 数组的值是 array 单元的值出现的次数。

参数

input

统计这个数组的值

返回值

返回一个关联数组，用 array 数组中的值作为键名，该值在数组中出现的次数作为值。

错误／异常

对数组里面的每个不是 string 和 integer 类型的元素抛出一个警告错误（E_WARNING）。

范例

Example #1 array_count_values() 例子

<?php
$array = array(1, "hello", 1, "world", "hello");
print_r(array_count_values($array));
?>

以上例程会输出：

Array
(
    [1] => 2
    [hello] => 2
    [world] => 1
)

参见

User Contributed Notes

jekkilekki at gmail dot com 17-Jan-2017 08:36
Simple example to count the values of a $key in an associative array:

/**
 * Associative Array Count Values
 *
 * Returns an array containing the number of values for a given $key in a given associative $array
 *
 * @param array $array The associative array to count values for
 * @param String $key The key to count values for
 * @return array A new array containing the counted values for the key in the original associative array
 */
function assc_array_count_values( $array, $key ) {
     foreach( $array as $row ) {
          $new_array[] = $row[$key];
     }
     return array_count_values( $new_array );
}
dhairya lakhera 17-Feb-2016 06:33
$array = array(1, true, 1, true, false,NULL);
var_dump(array_count_values($array));

//Warning: array_count_values(): Can only count STRING and INTEGER values!
jakubplus at gmail dot com 07-Apr-2014 08:36
In order to apply array_map with callback checking for localised values like city name, country name, you have to provide some sort of comparison array.

Here's an example of array_count_values for Polish city names. Just switch array_keys / array_values in order to obtain lowercase / uppercase.

$arr = array('Warsaw', 'Warsaw', 'Wroc?aw', 'Poznań', 'Kraków', 'waRsaw', 'Gdańsk', 'poznań', 'WROC?AW', 'kraków', 'GDA?SK');
$lowertoupperpolish = array(
    '?' => '?',
    '?' => '?',
    '?' => '?',
    '?' => '?',
    'ń' => '?',
    'ó' => 'ó',
    '?' => '?',
    '?' => '?',
    '?' => '?',
);
function lowers($n) {
    global $lowertoupperpolish;
    return strtolower(str_replace(array_values($lowertoupperpolish), array_keys($lowertoupperpolish), $n));
}
$result = array_count_values(array_map('lowers', $arr));

print_r($result); ...prints:

Array ( [warsaw] => 3 [wroc?aw] => 2 [poznań] => 2 [kraków] => 2 [gdańsk] => 2 )
Dominic Vonk 14-Dec-2013 01:11
The case-insensitive version:

<?php
function array_count_values_ci($array) {
    $newArray = array();
    foreach ($array as $values) {
        if (!array_key_exists(strtolower($values), $newArray)) {
            $newArray[strtolower($values)] = 0;
        }
        $newArray[strtolower($values)] += 1;
    }
    return $newArray;
}
?>
szczepan.krolgmail.c0m 17-Jan-2010 08:21
Here is a Version with one or more arrays, which have similar values in it:
Use $lower=true/false to ignore/set case Sensitiv.

<?php

$ar1[] = array("red","green","yellow","blue");
$ar1[] = array("green","yellow","brown","red","white","yellow");
$ar1[] = array("red","green","brown","blue","black","yellow");
#$ar1= array("red","green","brown","blue","black","red","green"); // Possible with one or multiple Array

$res = array_icount_values ($ar1);
print_r($res);

function array_icount_values($arr,$lower=true) {
     $arr2=array();
     if(!is_array($arr['0'])){$arr=array($arr);}
     foreach($arr as $k=> $v){
      foreach($v as $v2){
      if($lower==true) {$v2=strtolower($v2);}
      if(!isset($arr2[$v2])){
          $arr2[$v2]=1;
      }else{
           $arr2[$v2]++;
           }
    }
    }
    return $arr2;
}
/*
Will print:
Array
(
    [red] => 3
    [green] => 3
    [yellow] => 4
    [blue] => 2
    [brown] => 2
    [white] => 1
    [black] => 1
)
*/
?>
bluej100@gmail 25-Mar-2008 10:37
byron at byronrode dot co dot za, here are some benchmarks.

<?php
$haystack = Array();
for ($i = 0; $i < 1000000; $i++) {
  $haystack[] = rand(1, 2000);
}

$needle = rand(1, 2000);

echo "__array_count_values()__\n";
$start = microtime(true);
$startmem = memory_get_usage();
$counts = array_count_values($haystack);
$mem = memory_get_usage()-$startmem;
echo 'Count:'.$counts[$needle]."\n";
echo 'Time:'.(microtime(true) - $start)."\n";
echo 'Memory:'.$mem."\n\n";

echo "__array_keys()__\n";
$start = microtime(true);
$startmem = memory_get_usage();
$keys = array_keys($haystack, $needle);
$mem = memory_get_usage()-$startmem;
echo 'Count:'.count($keys)."\n";
echo 'Time:'.(microtime(true) - $start)."\n";
echo 'Memory:'.$mem."\n\n";

echo '__$needle_array[]__'."\n";
$start = microtime(true);
$startmem = memory_get_usage();
$x = count($haystack);
for($i = 0; $i < $x; $i++){
  if($haystack[$i] == $needle){
    $needle_array[] = $haystack[$i];
  }
}
$mem = memory_get_usage()-$startmem;
$number_of_instances = count($needle_array);
echo 'Count:'.$number_of_instances."\n";
echo 'Time:'.(microtime(true) - $start)."\n";
echo 'Memory:'.$mem."\n\n";

echo '__$number_of_instances++__'."\n";
$start = microtime(true);
$startmem = memory_get_usage();
$x = count($haystack);
$number_of_instances = 0;
for($i = 0; $i < $x; $i++){
  if($haystack[$i] == $needle){
    $number_of_instances++;
  }
}
$mem = memory_get_usage()-$startmem;
echo 'Count:'.$number_of_instances."\n";
echo 'Time:'.(microtime(true) - $start)."\n";
echo 'Memory:'.$mem."\n\n";
?>

[www]mytemp$ php array_count_test.php
__array_count_values()__
Count:515
Time:0.0607650279999
Memory:120328

__array_keys()__
Count:515
Time:0.0869138240814
Memory:33016

__$needle_array[]__
Count:515
Time:0.259949922562
Memory:24792

__$number_of_instances++__
Count:515
Time:0.258481025696
Memory:0

However, when you use an array of strings by calling md5(rand(1, 2000)), the performance boosts become less significant:

__array_count_values()__
Count:499
Time:0.491794109344
Memory:184328

__array_keys()__
Count:499
Time:0.36399102211
Memory:30072

__$needle_array[]__
Count:499
Time:0.568728923798
Memory:22104

__$number_of_instances++__
Count:499
Time:0.574353933334
Memory:0

Results are similar for string->string haystacks with foreach traversal.
Hayley Watson 13-Mar-2008 08:37
Yet Another case-insensitive version of array_count_values()

<?php
$ar = array('J. Karjalainen', 'J. Karjalainen', 60, '60', 'J. Karjalainen', 'j. karjalainen', 'Fastway', 'FASTWAY', 'Fastway', 'fastway', 'YUP');

$ar = array_count_values(array_map('strtolower', $ar));
?>
majerm at gmail dot com 18-Jun-2007 04:50
<?
function array_icount_values($array) {
    $ret_array = array();
    foreach($array as $value) $ret_array[strtolower($value)]++;
    return $ret_array;
}

$ar = array('J. Karjalainen', 'J. Karjalainen', 60, '60', 'J. Karjalainen', 'j. karjalainen', 'Fastway', 'FASTWAY', 'Fastway', 'fastway', 'YUP');
$ar = array_icount_values($ar);
?>

this prints:

Array
(
    [j. karjalainen] => 4
    [60] => 2
    [fastway] => 4
    [yup] => 1
)
rabies dot dostojevski at gmail dot com 21-Feb-2007 10:40
I couldn't find a function for counting the values with case-insensitive matching, so I wrote a quick and dirty solution myself:

<pre><?php
function array_icount_values($array) {
    $ret_array = array();
    foreach($array as $value) {
        foreach($ret_array as $key2 => $value2) {
            if(strtolower($key2) == strtolower($value)) {
                $ret_array[$key2]++;
                continue 2;
            }
        }
        $ret_array[$value] = 1;
    }
    return $ret_array;
}

$ar = array('J. Karjalainen', 'J. Karjalainen', 60, '60', 'J. Karjalainen', 'j. karjalainen', 'Fastway', 'FASTWAY', 'Fastway', 'fastway', 'YUP');
$ar2 = array_count_values($ar); // Normal matching
$ar = array_icount_values($ar); // Case-insensitive matching
print_r($ar2);
print_r($ar);
?></pre>

This prints:

Array
(
    [J. Karjalainen] => 3
    [60] => 2
    [j. karjalainen] => 1
    [Fastway] => 2
    [FASTWAY] => 1
    [fastway] => 1
    [YUP] => 1
)
Array
(
    [J. Karjalainen] => 4
    [60] => 2
    [Fastway] => 4
    [YUP] => 1
)

I don't know how efficient it is, but it seems to work. Needed this function in one of my scripts and thought I would share it.
coda at bobandgeorge dot com 14-Oct-2005 02:52
alwaysdrunk's comment only works if you can trust the client web browser. Using this function doesn't validate that every necessary field exists -- only that every field that was submitted has a value in it. Thus if an attacker wished to force a null value into one of the fields, he could (rather easily) construct a modified form without the field and submit THAT.

Besides, you really ought to be validating each field anyway if you're taking user input.
[Mr.A] 06-Mar-2005 11:59
I find a very simple solution to count values in multidimentional arrays (example for 2 levels) :

foreach ($array as $a) {
  foreach ($a as $b) {
    $count_values[$b]++;
  }
}
pmarcIatIgeneticsImedIharvardIedu 30-Jan-2003 02:42
array_count_values function does not work on multidimentional arrays.
If $score[][] is a bidimentional array, the command
"array_count_values ($score)" return the error message "Warning: Can only count STRING and INTEGER values!".
manuzhai (AT) php (DOT) net 16-Nov-2002 03:45
You might use serialize() to serialize your objects before analyzing their frequency. :)